mirror of
https://git.tartarus.org/simon/putty.git
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e3bcd35a37
tampering with the unencrypted public part of the key but leaving the private part intact ... we are now ultra-paranoid about RSA key files, and we check that the public part matches the private part _before_ we generate any signatures with them. [originally from svn r1021]
910 lines
23 KiB
C
910 lines
23 KiB
C
/*
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* Generic SSH public-key handling operations. In particular,
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* reading of SSH public-key files, and also the generic `sign'
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* operation for ssh2 (which checks the type of the key and
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* dispatches to the appropriate key-type specific function).
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <assert.h>
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#include "ssh.h"
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#define PUT_32BIT(cp, value) do { \
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(cp)[3] = (value); \
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(cp)[2] = (value) >> 8; \
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(cp)[1] = (value) >> 16; \
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(cp)[0] = (value) >> 24; } while (0)
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#define GET_32BIT(cp) \
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(((unsigned long)(unsigned char)(cp)[0] << 24) | \
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((unsigned long)(unsigned char)(cp)[1] << 16) | \
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((unsigned long)(unsigned char)(cp)[2] << 8) | \
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((unsigned long)(unsigned char)(cp)[3]))
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#define rsa_signature "SSH PRIVATE KEY FILE FORMAT 1.1\n"
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#define BASE64_TOINT(x) ( (x)-'A'<26 ? (x)-'A'+0 :\
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(x)-'a'<26 ? (x)-'a'+26 :\
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(x)-'0'<10 ? (x)-'0'+52 :\
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(x)=='+' ? 62 : \
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(x)=='/' ? 63 : 0 )
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static int loadrsakey_main(FILE *fp, struct RSAKey *key,
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char **commentptr, char *passphrase) {
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unsigned char buf[16384];
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unsigned char keybuf[16];
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int len;
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int i, j, ciphertype;
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int ret = 0;
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struct MD5Context md5c;
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char *comment;
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/* Slurp the whole file (minus the header) into a buffer. */
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len = fread(buf, 1, sizeof(buf), fp);
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fclose(fp);
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if (len < 0 || len == sizeof(buf))
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goto end; /* file too big or not read */
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i = 0;
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/*
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* A zero byte. (The signature includes a terminating NUL.)
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*/
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if (len-i < 1 || buf[i] != 0)
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goto end;
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i++;
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/* One byte giving encryption type, and one reserved uint32. */
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if (len-i < 1)
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goto end;
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ciphertype = buf[i];
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if (ciphertype != 0 && ciphertype != SSH_CIPHER_3DES)
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goto end;
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i++;
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if (len-i < 4)
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goto end; /* reserved field not present */
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if (buf[i] != 0 || buf[i+1] != 0 || buf[i+2] != 0 || buf[i+3] != 0)
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goto end; /* reserved field nonzero, panic! */
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i += 4;
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/* Now the serious stuff. An ordinary SSH 1 public key. */
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i += makekey(buf+i, key, NULL, 1);
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if (len-i < 0)
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goto end; /* overran */
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/* Next, the comment field. */
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j = GET_32BIT(buf+i);
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i += 4;
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if (len-i < j) goto end;
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comment = smalloc(j+1);
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if (comment) {
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memcpy(comment, buf+i, j);
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comment[j] = '\0';
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}
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i += j;
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if (commentptr)
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*commentptr = comment;
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if (key)
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key->comment = comment;
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if (!key) {
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return ciphertype != 0;
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}
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/*
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* Decrypt remainder of buffer.
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*/
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if (ciphertype) {
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MD5Init(&md5c);
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MD5Update(&md5c, passphrase, strlen(passphrase));
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MD5Final(keybuf, &md5c);
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des3_decrypt_pubkey(keybuf, buf+i, (len-i+7)&~7);
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memset(keybuf, 0, sizeof(keybuf)); /* burn the evidence */
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}
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/*
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* We are now in the secret part of the key. The first four
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* bytes should be of the form a, b, a, b.
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*/
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if (len-i < 4) goto end;
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if (buf[i] != buf[i+2] || buf[i+1] != buf[i+3]) { ret = -1; goto end; }
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i += 4;
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/*
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* After that, we have one further bignum which is our
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* decryption exponent, and then the three auxiliary values
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* (iqmp, q, p).
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*/
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i += makeprivate(buf+i, key);
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if (len-i < 0) goto end;
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i += ssh1_read_bignum(buf+i, &key->iqmp);
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if (len-i < 0) goto end;
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i += ssh1_read_bignum(buf+i, &key->q);
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if (len-i < 0) goto end;
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i += ssh1_read_bignum(buf+i, &key->p);
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if (len-i < 0) goto end;
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if (!rsa_verify(key)) {
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freersakey(key);
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ret = 0;
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} else
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ret = 1;
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end:
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memset(buf, 0, sizeof(buf)); /* burn the evidence */
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return ret;
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}
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int loadrsakey(char *filename, struct RSAKey *key, char *passphrase) {
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FILE *fp;
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unsigned char buf[64];
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fp = fopen(filename, "rb");
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if (!fp)
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return 0; /* doesn't even exist */
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/*
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* Read the first line of the file and see if it's a v1 private
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* key file.
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*/
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if (fgets(buf, sizeof(buf), fp) &&
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!strcmp(buf, rsa_signature)) {
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return loadrsakey_main(fp, key, NULL, passphrase);
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}
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/*
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* Otherwise, we have nothing. Return empty-handed.
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*/
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fclose(fp);
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return 0;
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}
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/*
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* See whether an RSA key is encrypted. Return its comment field as
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* well.
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*/
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int rsakey_encrypted(char *filename, char **comment) {
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FILE *fp;
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unsigned char buf[64];
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fp = fopen(filename, "rb");
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if (!fp)
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return 0; /* doesn't even exist */
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/*
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* Read the first line of the file and see if it's a v1 private
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* key file.
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*/
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if (fgets(buf, sizeof(buf), fp) &&
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!strcmp(buf, rsa_signature)) {
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return loadrsakey_main(fp, NULL, comment, NULL);
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}
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fclose(fp);
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return 0; /* wasn't the right kind of file */
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}
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/*
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* Save an RSA key file. Return nonzero on success.
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*/
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int saversakey(char *filename, struct RSAKey *key, char *passphrase) {
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unsigned char buf[16384];
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unsigned char keybuf[16];
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struct MD5Context md5c;
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unsigned char *p, *estart;
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FILE *fp;
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/*
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* Write the initial signature.
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*/
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p = buf;
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memcpy(p, rsa_signature, sizeof(rsa_signature));
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p += sizeof(rsa_signature);
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/*
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* One byte giving encryption type, and one reserved (zero)
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* uint32.
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*/
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*p++ = (passphrase ? SSH_CIPHER_3DES : 0);
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PUT_32BIT(p, 0); p += 4;
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/*
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* An ordinary SSH 1 public key consists of: a uint32
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* containing the bit count, then two bignums containing the
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* modulus and exponent respectively.
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*/
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PUT_32BIT(p, ssh1_bignum_bitcount(key->modulus)); p += 4;
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p += ssh1_write_bignum(p, key->modulus);
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p += ssh1_write_bignum(p, key->exponent);
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/*
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* A string containing the comment field.
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*/
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if (key->comment) {
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PUT_32BIT(p, strlen(key->comment)); p += 4;
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memcpy(p, key->comment, strlen(key->comment));
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p += strlen(key->comment);
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} else {
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PUT_32BIT(p, 0); p += 4;
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}
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/*
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* The encrypted portion starts here.
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*/
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estart = p;
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/*
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* Two bytes, then the same two bytes repeated.
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*/
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*p++ = random_byte();
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*p++ = random_byte();
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p[0] = p[-2]; p[1] = p[-1]; p += 2;
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/*
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* Four more bignums: the decryption exponent, then iqmp, then
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* q, then p.
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*/
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p += ssh1_write_bignum(p, key->private_exponent);
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p += ssh1_write_bignum(p, key->iqmp);
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p += ssh1_write_bignum(p, key->q);
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p += ssh1_write_bignum(p, key->p);
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/*
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* Now write zeros until the encrypted portion is a multiple of
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* 8 bytes.
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*/
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while ((p-estart) % 8)
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*p++ = '\0';
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/*
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* Now encrypt the encrypted portion.
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*/
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if (passphrase) {
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MD5Init(&md5c);
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MD5Update(&md5c, passphrase, strlen(passphrase));
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MD5Final(keybuf, &md5c);
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des3_encrypt_pubkey(keybuf, estart, p-estart);
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memset(keybuf, 0, sizeof(keybuf)); /* burn the evidence */
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}
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/*
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* Done. Write the result to the file.
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*/
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fp = fopen(filename, "wb");
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if (fp) {
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int ret = (fwrite(buf, 1, p-buf, fp) == (size_t)(p-buf));
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ret = ret && (fclose(fp) == 0);
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return ret;
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} else
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return 0;
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}
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/* ----------------------------------------------------------------------
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* SSH2 private key load/store functions.
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*/
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/*
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* PuTTY's own format for SSH2 keys is as follows:
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*
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* The file is text. Lines are terminated by CRLF, although CR-only
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* and LF-only are tolerated on input.
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*
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* The first line says "PuTTY-User-Key-File-1: " plus the name of the
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* algorithm ("ssh-dss", "ssh-rsa" etc. Although, of course, this
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* being PuTTY, "ssh-dss" is not supported.)
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*
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* The next line says "Encryption: " plus an encryption type.
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* Currently the only supported encryption types are "aes256-cbc"
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* and "none".
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*
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* The next line says "Comment: " plus the comment string.
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*
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* Next there is a line saying "Public-Lines: " plus a number N.
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* The following N lines contain a base64 encoding of the public
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* part of the key. This is encoded as the standard SSH2 public key
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* blob (with no initial length): so for RSA, for example, it will
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* read
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*
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* string "ssh-rsa"
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* mpint exponent
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* mpint modulus
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*
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* Next, there is a line saying "Private-Lines: " plus a number N,
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* and then N lines containing the (potentially encrypted) private
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* part of the key. For the key type "ssh-rsa", this will be
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* composed of
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*
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* mpint private_exponent
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* mpint p (the larger of the two primes)
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* mpint q (the smaller prime)
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* mpint iqmp (the inverse of q modulo p)
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* data padding (to reach a multiple of the cipher block size)
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*
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* Finally, there is a line saying "Private-Hash: " plus a hex
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* representation of a SHA-1 hash of the plaintext version of the
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* private part, including the final padding.
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*
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* If the key is encrypted, the encryption key is derived from the
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* passphrase by means of a succession of SHA-1 hashes. Each hash
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* is the hash of:
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*
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* uint32 sequence-number
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* string passphrase
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*
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* where the sequence-number increases from zero. As many of these
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* hashes are used as necessary.
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*
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* NOTE! It is important that all _public_ data can be verified
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* with reference to the _private_ data. There exist attacks based
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* on modifying the public key but leaving the private section
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* intact.
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*
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* With RSA, this is easy: verify that n = p*q, and also verify
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* that e*d == 1 modulo (p-1)(q-1). With DSA (if we were ever to
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* support it), we would need to store extra data in the private
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* section other than just x.
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*/
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static int read_header(FILE *fp, char *header) {
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int len = 39;
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int c;
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while (len > 0) {
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c = fgetc(fp);
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if (c == '\n' || c == '\r' || c == EOF)
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return 0; /* failure */
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if (c == ':') {
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c = fgetc(fp);
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if (c != ' ')
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return 0;
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*header = '\0';
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return 1; /* success! */
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}
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if (len == 0)
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return 0; /* failure */
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*header++ = c;
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len--;
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}
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return 0; /* failure */
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}
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static char *read_body(FILE *fp) {
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char *text;
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int len;
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int size;
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int c;
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size = 128;
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text = smalloc(size);
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len = 0;
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text[len] = '\0';
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while (1) {
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c = fgetc(fp);
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if (c == '\r' || c == '\n') {
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c = fgetc(fp);
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if (c != '\r' && c != '\n' && c != EOF)
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ungetc(c, fp);
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return text;
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}
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if (c == EOF) {
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sfree(text);
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return NULL;
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}
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if (len + 1 > size) {
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size += 128;
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text = srealloc(text, size);
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}
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text[len++] = c;
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text[len] = '\0';
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}
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}
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int base64_decode_atom(char *atom, unsigned char *out) {
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int vals[4];
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int i, v, len;
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unsigned word;
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char c;
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for (i = 0; i < 4; i++) {
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c = atom[i];
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if (c >= 'A' && c <= 'Z')
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v = c - 'A';
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else if (c >= 'a' && c <= 'z')
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v = c - 'a' + 26;
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else if (c >= '0' && c <= '9')
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v = c - '0' + 52;
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else if (c == '+')
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v = 62;
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else if (c == '/')
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v = 63;
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else if (c == '=')
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v = -1;
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else
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return 0; /* invalid atom */
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vals[i] = v;
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}
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if (vals[0] == -1 || vals[1] == -1)
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return 0;
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if (vals[2] == -1 && vals[3] != -1)
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return 0;
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if (vals[3] != -1)
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len = 3;
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else if (vals[2] != -1)
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len = 2;
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else
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len = 1;
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word = ((vals[0] << 18) |
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(vals[1] << 12) |
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((vals[2] & 0x3F) << 6) |
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(vals[3] & 0x3F));
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out[0] = (word >> 16) & 0xFF;
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if (len > 1)
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out[1] = (word >> 8) & 0xFF;
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if (len > 2)
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out[2] = word & 0xFF;
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return len;
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}
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static char *read_blob(FILE *fp, int nlines, int *bloblen) {
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unsigned char *blob;
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char *line;
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int linelen, len;
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int i, j, k;
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/* We expect at most 64 base64 characters, ie 48 real bytes, per line. */
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blob = smalloc(48 * nlines);
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len = 0;
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for (i = 0; i < nlines; i++) {
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line = read_body(fp);
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if (!line) {
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sfree(blob);
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return NULL;
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}
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linelen = strlen(line);
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if (linelen % 4 != 0 || linelen > 64) {
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sfree(blob);
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sfree(line);
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return NULL;
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}
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for (j = 0; j < linelen; j += 4) {
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k = base64_decode_atom(line+j, blob+len);
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if (!k) {
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sfree(line);
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sfree(blob);
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return NULL;
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}
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len += k;
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}
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sfree(line);
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}
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*bloblen = len;
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return blob;
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}
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/*
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* Magic error return value for when the passphrase is wrong.
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*/
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struct ssh2_userkey ssh2_wrong_passphrase = {
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NULL, NULL, NULL
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};
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struct ssh2_userkey *ssh2_load_userkey(char *filename, char *passphrase) {
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FILE *fp;
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char header[40], *b, *comment, *hash;
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const struct ssh_signkey *alg;
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struct ssh2_userkey *ret;
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int cipher, cipherblk;
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unsigned char *public_blob, *private_blob;
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int public_blob_len, private_blob_len;
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int i;
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ret = NULL; /* return NULL for most errors */
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comment = hash = NULL;
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public_blob = private_blob = NULL;
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fp = fopen(filename, "rb");
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if (!fp)
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goto error;
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/* Read the first header line which contains the key type. */
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if (!read_header(fp, header) || 0!=strcmp(header, "PuTTY-User-Key-File-1"))
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goto error;
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if ((b = read_body(fp)) == NULL)
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goto error;
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/* Select key algorithm structure. Currently only ssh-rsa. */
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if (!strcmp(b, "ssh-rsa"))
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alg = &ssh_rsa;
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else {
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sfree(b);
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goto error;
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}
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sfree(b);
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/* Read the Encryption header line. */
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if (!read_header(fp, header) || 0!=strcmp(header, "Encryption"))
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|
goto error;
|
|
if ((b = read_body(fp)) == NULL)
|
|
goto error;
|
|
if (!strcmp(b, "aes256-cbc")) {
|
|
cipher = 1; cipherblk = 16;
|
|
} else if (!strcmp(b, "none")) {
|
|
cipher = 0; cipherblk = 1;
|
|
} else {
|
|
sfree(b);
|
|
goto error;
|
|
}
|
|
sfree(b);
|
|
|
|
/* Read the Comment header line. */
|
|
if (!read_header(fp, header) || 0!=strcmp(header, "Comment"))
|
|
goto error;
|
|
if ((comment = read_body(fp)) == NULL)
|
|
goto error;
|
|
|
|
/* Read the Public-Lines header line and the public blob. */
|
|
if (!read_header(fp, header) || 0!=strcmp(header, "Public-Lines"))
|
|
goto error;
|
|
if ((b = read_body(fp)) == NULL)
|
|
goto error;
|
|
i = atoi(b);
|
|
sfree(b);
|
|
if ((public_blob = read_blob(fp, i, &public_blob_len)) == NULL)
|
|
goto error;
|
|
|
|
/* Read the Private-Lines header line and the Private blob. */
|
|
if (!read_header(fp, header) || 0!=strcmp(header, "Private-Lines"))
|
|
goto error;
|
|
if ((b = read_body(fp)) == NULL)
|
|
goto error;
|
|
i = atoi(b);
|
|
sfree(b);
|
|
if ((private_blob = read_blob(fp, i, &private_blob_len)) == NULL)
|
|
goto error;
|
|
|
|
/* Read the Private-Hash header line. */
|
|
if (!read_header(fp, header) || 0!=strcmp(header, "Private-Hash"))
|
|
goto error;
|
|
if ((hash = read_body(fp)) == NULL)
|
|
goto error;
|
|
|
|
fclose(fp);
|
|
fp = NULL;
|
|
|
|
/*
|
|
* Decrypt the private blob.
|
|
*/
|
|
if (cipher) {
|
|
unsigned char key[40];
|
|
SHA_State s;
|
|
int passlen;
|
|
|
|
if (!passphrase)
|
|
goto error;
|
|
if (private_blob_len % cipherblk)
|
|
goto error;
|
|
|
|
passlen = strlen(passphrase);
|
|
|
|
SHA_Init(&s);
|
|
SHA_Bytes(&s, "\0\0\0\0", 4);
|
|
SHA_Bytes(&s, passphrase, passlen);
|
|
SHA_Final(&s, key+0);
|
|
SHA_Init(&s);
|
|
SHA_Bytes(&s, "\0\0\0\1", 4);
|
|
SHA_Bytes(&s, passphrase, passlen);
|
|
SHA_Final(&s, key+20);
|
|
aes256_decrypt_pubkey(key, private_blob, private_blob_len);
|
|
}
|
|
|
|
/*
|
|
* Verify the private hash.
|
|
*/
|
|
{
|
|
char realhash[41];
|
|
unsigned char binary[20];
|
|
|
|
SHA_Simple(private_blob, private_blob_len, binary);
|
|
for (i = 0; i < 20; i++)
|
|
sprintf(realhash+2*i, "%02x", binary[i]);
|
|
|
|
if (strcmp(hash, realhash)) {
|
|
/* An incorrect hash is an unconditional Error if the key is
|
|
* unencrypted. Otherwise, it means Wrong Passphrase. */
|
|
ret = cipher ? SSH2_WRONG_PASSPHRASE : NULL;
|
|
goto error;
|
|
}
|
|
}
|
|
sfree(hash);
|
|
|
|
/*
|
|
* Create and return the key.
|
|
*/
|
|
ret = smalloc(sizeof(struct ssh2_userkey));
|
|
ret->alg = alg;
|
|
ret->comment = comment;
|
|
ret->data = alg->createkey(public_blob, public_blob_len,
|
|
private_blob, private_blob_len);
|
|
if (!ret->data) {
|
|
sfree(ret->comment);
|
|
sfree(ret);
|
|
ret = NULL;
|
|
}
|
|
sfree(public_blob);
|
|
sfree(private_blob);
|
|
return ret;
|
|
|
|
/*
|
|
* Error processing.
|
|
*/
|
|
error:
|
|
if (fp) fclose(fp);
|
|
if (comment) sfree(comment);
|
|
if (hash) sfree(hash);
|
|
if (public_blob) sfree(public_blob);
|
|
if (private_blob) sfree(private_blob);
|
|
return ret;
|
|
}
|
|
|
|
char *ssh2_userkey_loadpub(char *filename, char **algorithm, int *pub_blob_len) {
|
|
FILE *fp;
|
|
char header[40], *b;
|
|
const struct ssh_signkey *alg;
|
|
unsigned char *public_blob;
|
|
int public_blob_len;
|
|
int i;
|
|
|
|
public_blob = NULL;
|
|
|
|
fp = fopen(filename, "rb");
|
|
if (!fp)
|
|
goto error;
|
|
|
|
/* Read the first header line which contains the key type. */
|
|
if (!read_header(fp, header) || 0!=strcmp(header, "PuTTY-User-Key-File-1"))
|
|
goto error;
|
|
if ((b = read_body(fp)) == NULL)
|
|
goto error;
|
|
/* Select key algorithm structure. Currently only ssh-rsa. */
|
|
if (!strcmp(b, "ssh-rsa"))
|
|
alg = &ssh_rsa;
|
|
else {
|
|
sfree(b);
|
|
goto error;
|
|
}
|
|
sfree(b);
|
|
|
|
/* Read the Encryption header line. */
|
|
if (!read_header(fp, header) || 0!=strcmp(header, "Encryption"))
|
|
goto error;
|
|
if ((b = read_body(fp)) == NULL)
|
|
goto error;
|
|
sfree(b); /* we don't care */
|
|
|
|
/* Read the Comment header line. */
|
|
if (!read_header(fp, header) || 0!=strcmp(header, "Comment"))
|
|
goto error;
|
|
if ((b = read_body(fp)) == NULL)
|
|
goto error;
|
|
sfree(b); /* we don't care */
|
|
|
|
/* Read the Public-Lines header line and the public blob. */
|
|
if (!read_header(fp, header) || 0!=strcmp(header, "Public-Lines"))
|
|
goto error;
|
|
if ((b = read_body(fp)) == NULL)
|
|
goto error;
|
|
i = atoi(b);
|
|
sfree(b);
|
|
if ((public_blob = read_blob(fp, i, &public_blob_len)) == NULL)
|
|
goto error;
|
|
|
|
fclose(fp);
|
|
*pub_blob_len = public_blob_len;
|
|
*algorithm = alg->name;
|
|
return public_blob;
|
|
|
|
/*
|
|
* Error processing.
|
|
*/
|
|
error:
|
|
if (fp) fclose(fp);
|
|
if (public_blob) sfree(public_blob);
|
|
return NULL;
|
|
}
|
|
|
|
int ssh2_userkey_encrypted(char *filename, char **commentptr) {
|
|
FILE *fp;
|
|
char header[40], *b, *comment;
|
|
int ret;
|
|
|
|
if (commentptr) *commentptr = NULL;
|
|
|
|
fp = fopen(filename, "rb");
|
|
if (!fp)
|
|
return 0;
|
|
if (!read_header(fp, header) || 0!=strcmp(header, "PuTTY-User-Key-File-1")) {
|
|
fclose(fp); return 0;
|
|
}
|
|
if ((b = read_body(fp)) == NULL) {
|
|
fclose(fp); return 0;
|
|
}
|
|
sfree(b); /* we don't care about key type here */
|
|
/* Read the Encryption header line. */
|
|
if (!read_header(fp, header) || 0!=strcmp(header, "Encryption")) {
|
|
fclose(fp); return 0;
|
|
}
|
|
if ((b = read_body(fp)) == NULL) {
|
|
fclose(fp); return 0;
|
|
}
|
|
|
|
/* Read the Comment header line. */
|
|
if (!read_header(fp, header) || 0!=strcmp(header, "Comment")) {
|
|
fclose(fp); sfree(b); return 1;
|
|
}
|
|
if ((comment = read_body(fp)) == NULL) {
|
|
fclose(fp); sfree(b); return 1;
|
|
}
|
|
|
|
if (commentptr) *commentptr = comment;
|
|
|
|
fclose(fp);
|
|
if (!strcmp(b, "aes256-cbc"))
|
|
ret = 1;
|
|
else
|
|
ret = 0;
|
|
sfree(b);
|
|
return ret;
|
|
}
|
|
|
|
int base64_lines(int datalen) {
|
|
/* When encoding, we use 64 chars/line, which equals 48 real chars. */
|
|
return (datalen+47) / 48;
|
|
}
|
|
|
|
void base64_encode_atom(unsigned char *data, int n, char *out) {
|
|
static const char base64_chars[] =
|
|
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
|
|
|
|
unsigned word;
|
|
|
|
word = data[0] << 16;
|
|
if (n > 1)
|
|
word |= data[1] << 8;
|
|
if (n > 2)
|
|
word |= data[2];
|
|
out[0] = base64_chars[(word >> 18) & 0x3F];
|
|
out[1] = base64_chars[(word >> 12) & 0x3F];
|
|
if (n > 1)
|
|
out[2] = base64_chars[(word >> 6) & 0x3F];
|
|
else
|
|
out[2] = '=';
|
|
if (n > 2)
|
|
out[3] = base64_chars[word & 0x3F];
|
|
else
|
|
out[3] = '=';
|
|
}
|
|
|
|
void base64_encode(FILE *fp, unsigned char *data, int datalen) {
|
|
int linelen = 0;
|
|
char out[4];
|
|
int n;
|
|
|
|
while (datalen > 0) {
|
|
if (linelen >= 64) {
|
|
linelen = 0;
|
|
fputc('\n', fp);
|
|
}
|
|
n = (datalen < 3 ? datalen : 3);
|
|
base64_encode_atom(data, n, out);
|
|
data += n;
|
|
datalen -= n;
|
|
fwrite(out, 1, 4, fp);
|
|
linelen += 4;
|
|
}
|
|
fputc('\n', fp);
|
|
}
|
|
|
|
int ssh2_save_userkey(char *filename, struct ssh2_userkey *key, char *passphrase) {
|
|
FILE *fp;
|
|
unsigned char *pub_blob, *priv_blob, *priv_blob_encrypted;
|
|
int pub_blob_len, priv_blob_len, priv_encrypted_len;
|
|
int passlen;
|
|
int cipherblk;
|
|
int i;
|
|
char *cipherstr;
|
|
unsigned char priv_hash[20];
|
|
|
|
/*
|
|
* Fetch the key component blobs.
|
|
*/
|
|
pub_blob = key->alg->public_blob(key->data, &pub_blob_len);
|
|
priv_blob = key->alg->private_blob(key->data, &priv_blob_len);
|
|
if (!pub_blob || !priv_blob) {
|
|
sfree(pub_blob);
|
|
sfree(priv_blob);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Determine encryption details, and encrypt the private blob.
|
|
*/
|
|
if (passphrase) {
|
|
cipherstr = "aes256-cbc";
|
|
cipherblk = 16;
|
|
} else {
|
|
cipherstr = "none";
|
|
cipherblk = 1;
|
|
}
|
|
priv_encrypted_len = priv_blob_len + cipherblk - 1;
|
|
priv_encrypted_len -= priv_encrypted_len % cipherblk;
|
|
priv_blob_encrypted = smalloc(priv_encrypted_len);
|
|
memset(priv_blob_encrypted, 0, priv_encrypted_len);
|
|
memcpy(priv_blob_encrypted, priv_blob, priv_blob_len);
|
|
/* Create padding based on the SHA hash of the unpadded blob. This prevents
|
|
* too easy a known-plaintext attack on the last block. */
|
|
SHA_Simple(priv_blob, priv_blob_len, priv_hash);
|
|
assert(priv_encrypted_len - priv_blob_len < 20);
|
|
memcpy(priv_blob_encrypted + priv_blob_len, priv_hash,
|
|
priv_encrypted_len - priv_blob_len);
|
|
|
|
/* Now create the _real_ private hash. */
|
|
SHA_Simple(priv_blob_encrypted, priv_encrypted_len, priv_hash);
|
|
|
|
if (passphrase) {
|
|
char key[40];
|
|
SHA_State s;
|
|
|
|
passlen = strlen(passphrase);
|
|
|
|
SHA_Init(&s);
|
|
SHA_Bytes(&s, "\0\0\0\0", 4);
|
|
SHA_Bytes(&s, passphrase, passlen);
|
|
SHA_Final(&s, key+0);
|
|
SHA_Init(&s);
|
|
SHA_Bytes(&s, "\0\0\0\1", 4);
|
|
SHA_Bytes(&s, passphrase, passlen);
|
|
SHA_Final(&s, key+20);
|
|
aes256_encrypt_pubkey(key, priv_blob_encrypted, priv_encrypted_len);
|
|
}
|
|
|
|
fp = fopen(filename, "w");
|
|
if (!fp)
|
|
return 0;
|
|
fprintf(fp, "PuTTY-User-Key-File-1: %s\n", key->alg->name);
|
|
fprintf(fp, "Encryption: %s\n", cipherstr);
|
|
fprintf(fp, "Comment: %s\n", key->comment);
|
|
fprintf(fp, "Public-Lines: %d\n", base64_lines(pub_blob_len));
|
|
base64_encode(fp, pub_blob, pub_blob_len);
|
|
fprintf(fp, "Private-Lines: %d\n", base64_lines(priv_encrypted_len));
|
|
base64_encode(fp, priv_blob_encrypted, priv_encrypted_len);
|
|
fprintf(fp, "Private-Hash: ");
|
|
for (i = 0; i < 20; i++)
|
|
fprintf(fp, "%02x", priv_hash[i]);
|
|
fprintf(fp, "\n");
|
|
fclose(fp);
|
|
return 1;
|
|
}
|
|
|
|
/* ----------------------------------------------------------------------
|
|
* A function to determine which version of SSH to try on a private
|
|
* key file. Returns 0 on failure, 1 or 2 on success.
|
|
*/
|
|
int keyfile_version(char *filename) {
|
|
FILE *fp;
|
|
int i;
|
|
|
|
fp = fopen(filename, "r");
|
|
if (!fp)
|
|
return 0;
|
|
i = fgetc(fp);
|
|
fclose(fp);
|
|
if (i == 'S')
|
|
return 1; /* "SSH PRIVATE KEY FORMAT" etc */
|
|
if (i == 'P') /* "PuTTY-User-Key-File" etc */
|
|
return 2;
|
|
return 0; /* unrecognised or EOF */
|
|
}
|