+ return 0;
+}
+
+/* ----------------------------------------------------------------------
+ * SSH2 private key load/store functions.
+ */
+
+/*
+ * PuTTY's own format for SSH2 keys is as follows:
+ *
+ * The file is text. Lines are terminated by CRLF, although CR-only
+ * and LF-only are tolerated on input.
+ *
+ * The first line says "PuTTY-User-Key-File-1: " plus the name of the
+ * algorithm ("ssh-dss", "ssh-rsa" etc).
+ *
+ * The next line says "Encryption: " plus an encryption type.
+ * Currently the only supported encryption types are "aes256-cbc"
+ * and "none".
+ *
+ * The next line says "Comment: " plus the comment string.
+ *
+ * Next there is a line saying "Public-Lines: " plus a number N.
+ * The following N lines contain a base64 encoding of the public
+ * part of the key. This is encoded as the standard SSH2 public key
+ * blob (with no initial length): so for RSA, for example, it will
+ * read
+ *
+ * string "ssh-rsa"
+ * mpint exponent
+ * mpint modulus
+ *
+ * Next, there is a line saying "Private-Lines: " plus a number N,
+ * and then N lines containing the (potentially encrypted) private
+ * part of the key. For the key type "ssh-rsa", this will be
+ * composed of
+ *
+ * mpint private_exponent
+ * mpint p (the larger of the two primes)
+ * mpint q (the smaller prime)
+ * mpint iqmp (the inverse of q modulo p)
+ * data padding (to reach a multiple of the cipher block size)
+ *
+ * And for "ssh-dss", it will be composed of
+ *
+ * mpint x (the private key parameter)
+ * string hash (20-byte hash of mpints p || q || g)
+ *
+ * Finally, there is a line saying _either_
+ *
+ * - "Private-Hash: " plus a hex representation of a SHA-1 hash of
+ * the plaintext version of the private part, including the
+ * final padding.
+ *
+ * or
+ *
+ * - "Private-MAC: " plus a hex representation of a HMAC-SHA-1 of
+ * the plaintext version of the private part, including the
+ * final padding.
+ *
+ * The key to the MAC is itself a SHA-1 hash of:
+ *
+ * data "putty-private-key-file-mac-key"
+ * data passphrase
+ *
+ * Encrypted keys should have a MAC, whereas unencrypted ones must
+ * have a hash.
+ *
+ * If the key is encrypted, the encryption key is derived from the
+ * passphrase by means of a succession of SHA-1 hashes. Each hash
+ * is the hash of:
+ *
+ * uint32 sequence-number
+ * data passphrase
+ *
+ * where the sequence-number increases from zero. As many of these
+ * hashes are used as necessary.
+ *
+ * NOTE! It is important that all _public_ data can be verified
+ * with reference to the _private_ data. There exist attacks based
+ * on modifying the public key but leaving the private section
+ * intact.
+ *
+ * With RSA, this is easy: verify that n = p*q, and also verify
+ * that e*d == 1 modulo (p-1)(q-1). With DSA, we need to store
+ * extra data in the private section other than just x, namely a
+ * hash of p||q||g. (It's then easy to verify that y is equal to
+ * g^x mod p.)
+ */
+
+static int read_header(FILE * fp, char *header)
+{
+ int len = 39;
+ int c;
+
+ while (len > 0) {
+ c = fgetc(fp);
+ if (c == '\n' || c == '\r' || c == EOF)
+ return 0; /* failure */
+ if (c == ':') {
+ c = fgetc(fp);
+ if (c != ' ')
+ return 0;
+ *header = '\0';
+ return 1; /* success! */
+ }
+ if (len == 0)
+ return 0; /* failure */
+ *header++ = c;
+ len--;
+ }
+ return 0; /* failure */
+}
+
+static char *read_body(FILE * fp)
+{
+ char *text;
+ int len;
+ int size;
+ int c;
+
+ size = 128;
+ text = smalloc(size);
+ len = 0;
+ text[len] = '\0';
+
+ while (1) {
+ c = fgetc(fp);
+ if (c == '\r' || c == '\n') {
+ c = fgetc(fp);
+ if (c != '\r' && c != '\n' && c != EOF)
+ ungetc(c, fp);
+ return text;
+ }
+ if (c == EOF) {
+ sfree(text);
+ return NULL;
+ }
+ if (len + 1 > size) {
+ size += 128;
+ text = srealloc(text, size);
+ }
+ text[len++] = c;
+ text[len] = '\0';
+ }
+}
+
+int base64_decode_atom(char *atom, unsigned char *out)
+{
+ int vals[4];
+ int i, v, len;
+ unsigned word;
+ char c;
+
+ for (i = 0; i < 4; i++) {
+ c = atom[i];
+ if (c >= 'A' && c <= 'Z')
+ v = c - 'A';
+ else if (c >= 'a' && c <= 'z')
+ v = c - 'a' + 26;
+ else if (c >= '0' && c <= '9')
+ v = c - '0' + 52;
+ else if (c == '+')
+ v = 62;
+ else if (c == '/')
+ v = 63;
+ else if (c == '=')
+ v = -1;
+ else
+ return 0; /* invalid atom */
+ vals[i] = v;
+ }
+
+ if (vals[0] == -1 || vals[1] == -1)
+ return 0;
+ if (vals[2] == -1 && vals[3] != -1)
+ return 0;
+
+ if (vals[3] != -1)
+ len = 3;
+ else if (vals[2] != -1)
+ len = 2;
+ else
+ len = 1;
+
+ word = ((vals[0] << 18) |
+ (vals[1] << 12) | ((vals[2] & 0x3F) << 6) | (vals[3] & 0x3F));
+ out[0] = (word >> 16) & 0xFF;
+ if (len > 1)
+ out[1] = (word >> 8) & 0xFF;
+ if (len > 2)
+ out[2] = word & 0xFF;
+ return len;
+}
+
+static char *read_blob(FILE * fp, int nlines, int *bloblen)
+{
+ unsigned char *blob;
+ char *line;
+ int linelen, len;
+ int i, j, k;
+
+ /* We expect at most 64 base64 characters, ie 48 real bytes, per line. */
+ blob = smalloc(48 * nlines);
+ len = 0;
+ for (i = 0; i < nlines; i++) {
+ line = read_body(fp);
+ if (!line) {
+ sfree(blob);
+ return NULL;
+ }
+ linelen = strlen(line);
+ if (linelen % 4 != 0 || linelen > 64) {
+ sfree(blob);
+ sfree(line);
+ return NULL;
+ }
+ for (j = 0; j < linelen; j += 4) {
+ k = base64_decode_atom(line + j, blob + len);
+ if (!k) {
+ sfree(line);
+ sfree(blob);
+ return NULL;
+ }
+ len += k;
+ }
+ sfree(line);
+ }
+ *bloblen = len;
+ return blob;
+}
+
+/*
+ * Magic error return value for when the passphrase is wrong.
+ */
+struct ssh2_userkey ssh2_wrong_passphrase = {
+ NULL, NULL, NULL
+};
+
+struct ssh2_userkey *ssh2_load_userkey(char *filename, char *passphrase)
+{
+ FILE *fp;
+ char header[40], *b, *comment, *mac;
+ const struct ssh_signkey *alg;
+ struct ssh2_userkey *ret;
+ int cipher, cipherblk;
+ unsigned char *public_blob, *private_blob;
+ int public_blob_len, private_blob_len;
+ int i, is_mac;
+ int passlen = passphrase ? strlen(passphrase) : 0;
+
+ ret = NULL; /* return NULL for most errors */
+ comment = mac = NULL;
+ public_blob = private_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. */
+ if (!strcmp(b, "ssh-rsa"))
+ alg = &ssh_rsa;
+ else if (!strcmp(b, "ssh-dss"))
+ alg = &ssh_dss;
+ 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;
+ 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-MAC or Private-Hash header line. */
+ if (!read_header(fp, header))
+ goto error;
+ if (0 == strcmp(header, "Private-MAC")) {
+ if ((mac = read_body(fp)) == NULL)
+ goto error;
+ is_mac = 1;
+ } else if (0 == strcmp(header, "Private-Hash")) {
+ if ((mac = read_body(fp)) == NULL)
+ goto error;
+ is_mac = 0;
+ } else
+ goto error;
+
+ fclose(fp);
+ fp = NULL;
+
+ /*
+ * Decrypt the private blob.
+ */
+ if (cipher) {
+ unsigned char key[40];
+ SHA_State s;
+
+ if (!passphrase)
+ goto error;
+ if (private_blob_len % cipherblk)
+ goto error;
+
+ 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 realmac[41];
+ unsigned char binary[20];
+
+ if (is_mac) {
+ SHA_State s;
+ unsigned char mackey[20];
+ char header[] = "putty-private-key-file-mac-key";
+
+ if (!passphrase) /* can't have MAC in unencrypted key */
+ goto error;
+
+ SHA_Init(&s);
+ SHA_Bytes(&s, header, sizeof(header)-1);
+ SHA_Bytes(&s, passphrase, passlen);
+ SHA_Final(&s, mackey);
+
+ hmac_sha1_simple(mackey, 20, private_blob, private_blob_len,
+ binary);
+
+ memset(mackey, 0, sizeof(mackey));
+ memset(&s, 0, sizeof(s));
+ } else {
+ SHA_Simple(private_blob, private_blob_len, binary);
+ }
+ for (i = 0; i < 20; i++)
+ sprintf(realmac + 2 * i, "%02x", binary[i]);
+
+ if (strcmp(mac, realmac)) {
+ /* An incorrect MAC is an unconditional Error if the key is
+ * unencrypted. Otherwise, it means Wrong Passphrase. */
+ ret = cipher ? SSH2_WRONG_PASSPHRASE : NULL;
+ goto error;
+ }
+ }
+ sfree(mac);
+
+ /*
+ * 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 (mac)
+ sfree(mac);
+ 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 if (!strcmp(b, "ssh-dss"))
+ alg = &ssh_dss;
+ 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, is_mac;
+ char *cipherstr;
+ unsigned char priv_mac[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_mac);
+ assert(priv_encrypted_len - priv_blob_len < 20);
+ memcpy(priv_blob_encrypted + priv_blob_len, priv_mac,
+ priv_encrypted_len - priv_blob_len);
+
+ /* Now create the private MAC. */
+ if (passphrase) {
+ SHA_State s;
+ unsigned char mackey[20];
+ char header[] = "putty-private-key-file-mac-key";
+
+ passlen = strlen(passphrase);
+
+ SHA_Init(&s);
+ SHA_Bytes(&s, header, sizeof(header)-1);
+ SHA_Bytes(&s, passphrase, passlen);
+ SHA_Final(&s, mackey);
+
+ hmac_sha1_simple(mackey, 20,
+ priv_blob_encrypted, priv_encrypted_len,
+ priv_mac);
+ is_mac = 1;
+
+ memset(mackey, 0, sizeof(mackey));
+ memset(&s, 0, sizeof(s));
+ } else {
+ SHA_Simple(priv_blob_encrypted, priv_encrypted_len, priv_mac);
+ is_mac = 0;
+ }
+
+ 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);
+
+ memset(key, 0, sizeof(key));
+ memset(&s, 0, sizeof(s));
+ }
+
+ 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);
+ if (is_mac)
+ fprintf(fp, "Private-MAC: ");
+ else
+ fprintf(fp, "Private-Hash: ");
+ for (i = 0; i < 20; i++)
+ fprintf(fp, "%02x", priv_mac[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 */