| 1 | /* |
| 2 | * Read SSH public keys from files. |
| 3 | * |
| 4 | * First implementation: only supports unencrypted SSH 1.1 format |
| 5 | * RSA keys. Encryption, and SSH 2 DSS keys, to be supported later. |
| 6 | */ |
| 7 | |
| 8 | #include <stdio.h> |
| 9 | |
| 10 | #include <stdio.h> /* FIXME */ |
| 11 | #include <stdarg.h> /* FIXME */ |
| 12 | #include <windows.h> /* FIXME */ |
| 13 | #include "putty.h" /* FIXME */ |
| 14 | |
| 15 | #include "ssh.h" |
| 16 | |
| 17 | #define GET_32BIT(cp) \ |
| 18 | (((unsigned long)(unsigned char)(cp)[0] << 24) | \ |
| 19 | ((unsigned long)(unsigned char)(cp)[1] << 16) | \ |
| 20 | ((unsigned long)(unsigned char)(cp)[2] << 8) | \ |
| 21 | ((unsigned long)(unsigned char)(cp)[3])) |
| 22 | |
| 23 | #define rsa_signature "SSH PRIVATE KEY FILE FORMAT 1.1\n" |
| 24 | |
| 25 | int loadrsakey(char *filename, struct RSAKey *key, char *passphrase) { |
| 26 | FILE *fp; |
| 27 | unsigned char buf[16384]; |
| 28 | unsigned char keybuf[16]; |
| 29 | int len; |
| 30 | int i, j, ciphertype; |
| 31 | int ret = 0; |
| 32 | struct MD5Context md5c; |
| 33 | |
| 34 | fp = fopen(filename, "rb"); |
| 35 | if (!fp) |
| 36 | goto end; |
| 37 | |
| 38 | /* Slurp the whole file into a buffer. */ |
| 39 | len = fread(buf, 1, sizeof(buf), fp); |
| 40 | fclose(fp); |
| 41 | if (len < 0 || len == sizeof(buf)) |
| 42 | goto end; /* file too big or not read */ |
| 43 | |
| 44 | if (len < sizeof(rsa_signature) || |
| 45 | memcmp(buf, rsa_signature, sizeof(rsa_signature)) != 0) |
| 46 | goto end; /* failure to have sig at front */ |
| 47 | |
| 48 | i = sizeof(rsa_signature); |
| 49 | |
| 50 | /* Next, one byte giving encryption type, and one reserved uint32. */ |
| 51 | if (len-i < 1) |
| 52 | goto end; |
| 53 | ciphertype = buf[i]; |
| 54 | if (ciphertype != 0 && ciphertype != SSH_CIPHER_3DES) |
| 55 | goto end; |
| 56 | i++; |
| 57 | if (len-i < 4) |
| 58 | goto end; /* reserved field not present */ |
| 59 | if (buf[i] != 0 || buf[i+1] != 0 || buf[i+2] != 0 || buf[i+3] != 0) |
| 60 | goto end; /* reserved field nonzero, panic! */ |
| 61 | i += 4; |
| 62 | |
| 63 | /* Now the serious stuff. An ordinary SSH 1 public key. */ |
| 64 | i += makekey(buf+i, key, NULL, 1); |
| 65 | if (len-i < 0) |
| 66 | goto end; /* overran */ |
| 67 | |
| 68 | /* Next, the comment field. */ |
| 69 | j = GET_32BIT(buf+i); |
| 70 | if (len-i < 4+j) goto end; i += 4+j; |
| 71 | /* |
| 72 | * FIXME: might need to use this string. |
| 73 | */ |
| 74 | |
| 75 | /* |
| 76 | * Decrypt remainder of buffer. |
| 77 | */ |
| 78 | if (ciphertype) { |
| 79 | MD5Init(&md5c); |
| 80 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
| 81 | MD5Final(keybuf, &md5c); |
| 82 | des3_decrypt_pubkey(keybuf, buf+i, (len-i+7)&~7); |
| 83 | memset(keybuf, 0, sizeof(buf)); /* burn the evidence */ |
| 84 | } |
| 85 | |
| 86 | /* |
| 87 | * We are now in the secret part of the key. The first four |
| 88 | * bytes should be of the form a, b, a, b. |
| 89 | */ |
| 90 | if (len-i < 4) goto end; |
| 91 | if (buf[i] != buf[i+2] || buf[i+1] != buf[i+3]) { ret = -1; goto end; } |
| 92 | i += 4; |
| 93 | |
| 94 | /* |
| 95 | * After that, we have one further bignum which is our |
| 96 | * decryption modulus, and then we're done. |
| 97 | */ |
| 98 | i += makeprivate(buf+i, key); |
| 99 | if (len-i < 0) goto end; |
| 100 | |
| 101 | ret = 1; |
| 102 | end: |
| 103 | memset(buf, 0, sizeof(buf)); /* burn the evidence */ |
| 104 | return ret; |
| 105 | } |
| 106 | |
| 107 | /* |
| 108 | * See whether an RSA key is encrypted. |
| 109 | */ |
| 110 | int rsakey_encrypted(char *filename) { |
| 111 | FILE *fp; |
| 112 | unsigned char buf[1+sizeof(rsa_signature)]; |
| 113 | int len; |
| 114 | |
| 115 | fp = fopen(filename, "rb"); |
| 116 | if (!fp) |
| 117 | return 0; /* doesn't even exist */ |
| 118 | |
| 119 | /* Slurp the whole file into a buffer. */ |
| 120 | len = fread(buf, 1, sizeof(buf), fp); |
| 121 | fclose(fp); |
| 122 | if (len < sizeof(buf)) |
| 123 | return 0; /* not even valid */ |
| 124 | if (buf[sizeof(buf)-1]) |
| 125 | return 1; /* encrypted */ |
| 126 | return 0; |
| 127 | } |