2 * Generic SSH public-key handling operations. In particular,
3 * reading of SSH public-key files, and also the generic `sign'
4 * operation for ssh2 (which checks the type of the key and
5 * dispatches to the appropriate key-type specific function).
13 #define PUT_32BIT(cp, value) do { \
15 (cp)[2] = (value) >> 8; \
16 (cp)[1] = (value) >> 16; \
17 (cp)[0] = (value) >> 24; } while (0)
19 #define GET_32BIT(cp) \
20 (((unsigned long)(unsigned char)(cp)[0] << 24) | \
21 ((unsigned long)(unsigned char)(cp)[1] << 16) | \
22 ((unsigned long)(unsigned char)(cp)[2] << 8) | \
23 ((unsigned long)(unsigned char)(cp)[3]))
25 #define rsa_signature "SSH PRIVATE KEY FILE FORMAT 1.1\n"
27 #define BASE64_TOINT(x) ( (x)-'A'<26 ? (x)-'A'+0 :\
28 (x)-'a'<26 ? (x)-'a'+26 :\
29 (x)-'0'<10 ? (x)-'0'+52 :\
33 static int loadrsakey_main(FILE *fp
, struct RSAKey
*key
, struct RSAAux
*aux
,
34 char **commentptr
, char *passphrase
) {
35 unsigned char buf
[16384];
36 unsigned char keybuf
[16];
40 struct MD5Context md5c
;
43 /* Slurp the whole file (minus the header) into a buffer. */
44 len
= fread(buf
, 1, sizeof(buf
), fp
);
46 if (len
< 0 || len
== sizeof(buf
))
47 goto end
; /* file too big or not read */
52 * A zero byte. (The signature includes a terminating NUL.)
54 if (len
-i
< 1 || buf
[i
] != 0)
58 /* One byte giving encryption type, and one reserved uint32. */
62 if (ciphertype
!= 0 && ciphertype
!= SSH_CIPHER_3DES
)
66 goto end
; /* reserved field not present */
67 if (buf
[i
] != 0 || buf
[i
+1] != 0 || buf
[i
+2] != 0 || buf
[i
+3] != 0)
68 goto end
; /* reserved field nonzero, panic! */
71 /* Now the serious stuff. An ordinary SSH 1 public key. */
72 i
+= makekey(buf
+i
, key
, NULL
, 1);
74 goto end
; /* overran */
76 /* Next, the comment field. */
79 if (len
-i
< j
) goto end
;
80 comment
= malloc(j
+1);
82 memcpy(comment
, buf
+i
, j
);
87 *commentptr
= comment
;
89 key
->comment
= comment
;
91 return ciphertype
!= 0;
95 * Decrypt remainder of buffer.
99 MD5Update(&md5c
, passphrase
, strlen(passphrase
));
100 MD5Final(keybuf
, &md5c
);
101 des3_decrypt_pubkey(keybuf
, buf
+i
, (len
-i
+7)&~7);
102 memset(keybuf
, 0, sizeof(keybuf
)); /* burn the evidence */
106 * We are now in the secret part of the key. The first four
107 * bytes should be of the form a, b, a, b.
109 if (len
-i
< 4) goto end
;
110 if (buf
[i
] != buf
[i
+2] || buf
[i
+1] != buf
[i
+3]) { ret
= -1; goto end
; }
114 * After that, we have one further bignum which is our
115 * decryption exponent, and then the three auxiliary values
118 i
+= makeprivate(buf
+i
, key
);
119 if (len
-i
< 0) goto end
;
121 i
+= ssh1_read_bignum(buf
+i
, &aux
->iqmp
);
122 if (len
-i
< 0) goto end
;
123 i
+= ssh1_read_bignum(buf
+i
, &aux
->q
);
124 if (len
-i
< 0) goto end
;
125 i
+= ssh1_read_bignum(buf
+i
, &aux
->p
);
126 if (len
-i
< 0) goto end
;
131 memset(buf
, 0, sizeof(buf
)); /* burn the evidence */
135 int loadrsakey(char *filename
, struct RSAKey
*key
, struct RSAAux
*aux
,
138 unsigned char buf
[64];
140 fp
= fopen(filename
, "rb");
142 return 0; /* doesn't even exist */
145 * Read the first line of the file and see if it's a v1 private
148 if (fgets(buf
, sizeof(buf
), fp
) &&
149 !strcmp(buf
, rsa_signature
)) {
150 return loadrsakey_main(fp
, key
, aux
, NULL
, passphrase
);
154 * Otherwise, we have nothing. Return empty-handed.
161 * See whether an RSA key is encrypted. Return its comment field as
164 int rsakey_encrypted(char *filename
, char **comment
) {
166 unsigned char buf
[64];
168 fp
= fopen(filename
, "rb");
170 return 0; /* doesn't even exist */
173 * Read the first line of the file and see if it's a v1 private
176 if (fgets(buf
, sizeof(buf
), fp
) &&
177 !strcmp(buf
, rsa_signature
)) {
178 return loadrsakey_main(fp
, NULL
, NULL
, comment
, NULL
);
181 return 0; /* wasn't the right kind of file */
185 * Save an RSA key file. Return nonzero on success.
187 int saversakey(char *filename
, struct RSAKey
*key
, struct RSAAux
*aux
,
189 unsigned char buf
[16384];
190 unsigned char keybuf
[16];
191 struct MD5Context md5c
;
196 * Write the initial signature.
199 memcpy(p
, rsa_signature
, sizeof(rsa_signature
));
200 p
+= sizeof(rsa_signature
);
203 * One byte giving encryption type, and one reserved (zero)
206 *p
++ = (passphrase ? SSH_CIPHER_3DES
: 0);
207 PUT_32BIT(p
, 0); p
+= 4;
210 * An ordinary SSH 1 public key consists of: a uint32
211 * containing the bit count, then two bignums containing the
212 * modulus and exponent respectively.
214 PUT_32BIT(p
, ssh1_bignum_bitcount(key
->modulus
)); p
+= 4;
215 p
+= ssh1_write_bignum(p
, key
->modulus
);
216 p
+= ssh1_write_bignum(p
, key
->exponent
);
219 * A string containing the comment field.
222 PUT_32BIT(p
, strlen(key
->comment
)); p
+= 4;
223 memcpy(p
, key
->comment
, strlen(key
->comment
));
224 p
+= strlen(key
->comment
);
226 PUT_32BIT(p
, 0); p
+= 4;
230 * The encrypted portion starts here.
235 * Two bytes, then the same two bytes repeated.
237 *p
++ = random_byte();
238 *p
++ = random_byte();
239 p
[0] = p
[-2]; p
[1] = p
[-1]; p
+= 2;
242 * Four more bignums: the decryption exponent, then iqmp, then
245 p
+= ssh1_write_bignum(p
, key
->private_exponent
);
246 p
+= ssh1_write_bignum(p
, aux
->iqmp
);
247 p
+= ssh1_write_bignum(p
, aux
->q
);
248 p
+= ssh1_write_bignum(p
, aux
->p
);
251 * Now write zeros until the encrypted portion is a multiple of
254 while ((p
-estart
) % 8)
258 * Now encrypt the encrypted portion.
262 MD5Update(&md5c
, passphrase
, strlen(passphrase
));
263 MD5Final(keybuf
, &md5c
);
264 des3_encrypt_pubkey(keybuf
, estart
, p
-estart
);
265 memset(keybuf
, 0, sizeof(keybuf
)); /* burn the evidence */
269 * Done. Write the result to the file.
271 fp
= fopen(filename
, "wb");
273 int ret
= (fwrite(buf
, 1, p
-buf
, fp
) == (size_t)(p
-buf
));
274 ret
= ret
&& (fclose(fp
) == 0);