зеркало из https://github.com/github/putty.git
128 строки
3.5 KiB
C
128 строки
3.5 KiB
C
/*
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* Read SSH public keys from files.
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*
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* First implementation: only supports unencrypted SSH 1.1 format
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* RSA keys. Encryption, and SSH 2 DSS keys, to be supported later.
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*/
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#include <stdio.h>
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#include <stdio.h> /* FIXME */
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#include <stdarg.h> /* FIXME */
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#include <windows.h> /* FIXME */
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#include "putty.h" /* FIXME */
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#include "ssh.h"
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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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int loadrsakey(char *filename, struct RSAKey *key, char *passphrase) {
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FILE *fp;
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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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fp = fopen(filename, "rb");
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if (!fp)
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goto end;
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/* Slurp the whole file 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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if (len < sizeof(rsa_signature) ||
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memcmp(buf, rsa_signature, sizeof(rsa_signature)) != 0)
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goto end; /* failure to have sig at front */
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i = sizeof(rsa_signature);
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/* Next, 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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if (len-i < 4+j) goto end; i += 4+j;
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/*
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* FIXME: might need to use this string.
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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(buf)); /* 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 modulus, and then we're done.
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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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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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/*
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* See whether an RSA key is encrypted.
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*/
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int rsakey_encrypted(char *filename) {
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FILE *fp;
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unsigned char buf[1+sizeof(rsa_signature)];
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int len;
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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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/* Slurp the whole file 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 < sizeof(buf))
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return 0; /* not even valid */
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if (buf[sizeof(buf)-1])
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return 1; /* encrypted */
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return 0;
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}
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