/*
- * Read SSH public keys from files.
- *
- * First implementation: only supports unencrypted SSH 1.1 format
- * RSA keys. Encryption, and SSH 2 DSS keys, to be supported later.
+ * Generic SSH public-key handling operations. In particular,
+ * reading of SSH public-key files, and also the generic `sign'
+ * operation for ssh2 (which checks the type of the key and
+ * dispatches to the appropriate key-type specific function).
*/
#include <stdio.h>
-
-#include <stdio.h> /* FIXME */
-#include <stdarg.h> /* FIXME */
-#include <windows.h> /* FIXME */
-#include "putty.h" /* FIXME */
+#include <stdlib.h>
#include "ssh.h"
+#define PUT_32BIT(cp, value) do { \
+ (cp)[3] = (value); \
+ (cp)[2] = (value) >> 8; \
+ (cp)[1] = (value) >> 16; \
+ (cp)[0] = (value) >> 24; } while (0)
+
#define GET_32BIT(cp) \
(((unsigned long)(unsigned char)(cp)[0] << 24) | \
((unsigned long)(unsigned char)(cp)[1] << 16) | \
#define rsa_signature "SSH PRIVATE KEY FILE FORMAT 1.1\n"
-int loadrsakey(char *filename, struct RSAKey *key, char *passphrase) {
- FILE *fp;
+#define BASE64_TOINT(x) ( (x)-'A'<26 ? (x)-'A'+0 :\
+ (x)-'a'<26 ? (x)-'a'+26 :\
+ (x)-'0'<10 ? (x)-'0'+52 :\
+ (x)=='+' ? 62 : \
+ (x)=='/' ? 63 : 0 )
+
+static int loadrsakey_main(FILE *fp, struct RSAKey *key, struct RSAAux *aux,
+ char **commentptr, char *passphrase) {
unsigned char buf[16384];
unsigned char keybuf[16];
int len;
int i, j, ciphertype;
int ret = 0;
struct MD5Context md5c;
+ char *comment;
- fp = fopen(filename, "rb");
- if (!fp)
- goto end;
-
- /* Slurp the whole file into a buffer. */
+ /* Slurp the whole file (minus the header) into a buffer. */
len = fread(buf, 1, sizeof(buf), fp);
fclose(fp);
if (len < 0 || len == sizeof(buf))
goto end; /* file too big or not read */
- if (len < sizeof(rsa_signature) ||
- memcmp(buf, rsa_signature, sizeof(rsa_signature)) != 0)
- goto end; /* failure to have sig at front */
+ i = 0;
- i = sizeof(rsa_signature);
+ /*
+ * A zero byte. (The signature includes a terminating NUL.)
+ */
+ if (len-i < 1 || buf[i] != 0)
+ goto end;
+ i++;
- /* Next, one byte giving encryption type, and one reserved uint32. */
+ /* One byte giving encryption type, and one reserved uint32. */
if (len-i < 1)
goto end;
ciphertype = buf[i];
j = GET_32BIT(buf+i);
i += 4;
if (len-i < j) goto end;
- key->comment = malloc(j+1);
- if (key->comment) {
- memcpy(key->comment, buf+i, j);
- key->comment[j] = '\0';
+ comment = smalloc(j+1);
+ if (comment) {
+ memcpy(comment, buf+i, j);
+ comment[j] = '\0';
}
i += j;
+ if (commentptr)
+ *commentptr = comment;
+ if (key)
+ key->comment = comment;
+ if (!key) {
+ return ciphertype != 0;
+ }
/*
* Decrypt remainder of buffer.
/*
* After that, we have one further bignum which is our
- * decryption modulus, and then we're done.
+ * decryption exponent, and then the three auxiliary values
+ * (iqmp, q, p).
*/
i += makeprivate(buf+i, key);
if (len-i < 0) goto end;
+ if (aux) {
+ i += ssh1_read_bignum(buf+i, &aux->iqmp);
+ if (len-i < 0) goto end;
+ i += ssh1_read_bignum(buf+i, &aux->q);
+ if (len-i < 0) goto end;
+ i += ssh1_read_bignum(buf+i, &aux->p);
+ if (len-i < 0) goto end;
+ }
ret = 1;
end:
return ret;
}
+int loadrsakey(char *filename, struct RSAKey *key, struct RSAAux *aux,
+ char *passphrase) {
+ FILE *fp;
+ unsigned char buf[64];
+
+ fp = fopen(filename, "rb");
+ if (!fp)
+ return 0; /* doesn't even exist */
+
+ /*
+ * Read the first line of the file and see if it's a v1 private
+ * key file.
+ */
+ if (fgets(buf, sizeof(buf), fp) &&
+ !strcmp(buf, rsa_signature)) {
+ return loadrsakey_main(fp, key, aux, NULL, passphrase);
+ }
+
+ /*
+ * Otherwise, we have nothing. Return empty-handed.
+ */
+ fclose(fp);
+ return 0;
+}
+
/*
- * See whether an RSA key is encrypted.
+ * See whether an RSA key is encrypted. Return its comment field as
+ * well.
*/
-int rsakey_encrypted(char *filename) {
+int rsakey_encrypted(char *filename, char **comment) {
FILE *fp;
- unsigned char buf[1+sizeof(rsa_signature)];
- int len;
+ unsigned char buf[64];
fp = fopen(filename, "rb");
if (!fp)
return 0; /* doesn't even exist */
- /* Slurp the whole file into a buffer. */
- len = fread(buf, 1, sizeof(buf), fp);
+ /*
+ * Read the first line of the file and see if it's a v1 private
+ * key file.
+ */
+ if (fgets(buf, sizeof(buf), fp) &&
+ !strcmp(buf, rsa_signature)) {
+ return loadrsakey_main(fp, NULL, NULL, comment, NULL);
+ }
fclose(fp);
- if (len < sizeof(buf))
- return 0; /* not even valid */
- if (buf[sizeof(buf)-1])
- return 1; /* encrypted */
- return 0;
+ return 0; /* wasn't the right kind of file */
+}
+
+/*
+ * Save an RSA key file. Return nonzero on success.
+ */
+int saversakey(char *filename, struct RSAKey *key, struct RSAAux *aux,
+ char *passphrase) {
+ unsigned char buf[16384];
+ unsigned char keybuf[16];
+ struct MD5Context md5c;
+ unsigned char *p, *estart;
+ FILE *fp;
+
+ /*
+ * Write the initial signature.
+ */
+ p = buf;
+ memcpy(p, rsa_signature, sizeof(rsa_signature));
+ p += sizeof(rsa_signature);
+
+ /*
+ * One byte giving encryption type, and one reserved (zero)
+ * uint32.
+ */
+ *p++ = (passphrase ? SSH_CIPHER_3DES : 0);
+ PUT_32BIT(p, 0); p += 4;
+
+ /*
+ * An ordinary SSH 1 public key consists of: a uint32
+ * containing the bit count, then two bignums containing the
+ * modulus and exponent respectively.
+ */
+ PUT_32BIT(p, ssh1_bignum_bitcount(key->modulus)); p += 4;
+ p += ssh1_write_bignum(p, key->modulus);
+ p += ssh1_write_bignum(p, key->exponent);
+
+ /*
+ * A string containing the comment field.
+ */
+ if (key->comment) {
+ PUT_32BIT(p, strlen(key->comment)); p += 4;
+ memcpy(p, key->comment, strlen(key->comment));
+ p += strlen(key->comment);
+ } else {
+ PUT_32BIT(p, 0); p += 4;
+ }
+
+ /*
+ * The encrypted portion starts here.
+ */
+ estart = p;
+
+ /*
+ * Two bytes, then the same two bytes repeated.
+ */
+ *p++ = random_byte();
+ *p++ = random_byte();
+ p[0] = p[-2]; p[1] = p[-1]; p += 2;
+
+ /*
+ * Four more bignums: the decryption exponent, then iqmp, then
+ * q, then p.
+ */
+ p += ssh1_write_bignum(p, key->private_exponent);
+ p += ssh1_write_bignum(p, aux->iqmp);
+ p += ssh1_write_bignum(p, aux->q);
+ p += ssh1_write_bignum(p, aux->p);
+
+ /*
+ * Now write zeros until the encrypted portion is a multiple of
+ * 8 bytes.
+ */
+ while ((p-estart) % 8)
+ *p++ = '\0';
+
+ /*
+ * Now encrypt the encrypted portion.
+ */
+ if (passphrase) {
+ MD5Init(&md5c);
+ MD5Update(&md5c, passphrase, strlen(passphrase));
+ MD5Final(keybuf, &md5c);
+ des3_encrypt_pubkey(keybuf, estart, p-estart);
+ memset(keybuf, 0, sizeof(keybuf)); /* burn the evidence */
+ }
+
+ /*
+ * Done. Write the result to the file.
+ */
+ fp = fopen(filename, "wb");
+ if (fp) {
+ int ret = (fwrite(buf, 1, p-buf, fp) == (size_t)(p-buf));
+ ret = ret && (fclose(fp) == 0);
+ return ret;
+ } else
+ return 0;
}
projects / u / mdw / putty / blobdiff