3 files changed, 106 insertions, 0 deletions

diff --git a/include/otputil.h b/include/otputil.h
index 13420fc..b6d6112 100644
--- a/include/otputil.h
+++ b/include/otputil.h
@@ -173,6 +173,8 @@
 #define OTPUTIL_OTP_SEED_MIN_LEN    1
 #define OTPUTIL_OTP_SEED_MAX_LEN    16
 
+#define OTPUTIL_SKEY_PASS_MAX_LEN   127
+
 
 /////////////////
 //             //
@@ -398,6 +400,13 @@ otputil_otp_str(
 #pragma mark S/KEY functions (RFC 1760)
 
 _OTPUTIL_F int
+otputil_skey_code(
+         const char *                  skey_pass,
+         int                           skey_seq,
+         uint64_t *                    skey_resultp );
+
+
+_OTPUTIL_F int
 otputil_skey_dict_value(
          const char *                  word );
 
@@ -407,6 +416,14 @@ otputil_skey_dict_word(
          int                           value );
 
 
+_OTPUTIL_F char *
+otputil_skey_str(
+         const char *                  skey_pass,
+         int                           skey_seq,
+         char *                        dst,
+         size_t                        dstlen );
+
+
 //---------------//
 // TOTP functions //
 //---------------//
diff --git a/lib/libotputil/libotputil.sym b/lib/libotputil/libotputil.sym
index c3faedb..cf898f6 100644
--- a/lib/libotputil/libotputil.sym
+++ b/lib/libotputil/libotputil.sym
@@ -93,8 +93,10 @@ otputil_otp_encode_len
 otputil_otp_str
 #
 # S/KEY functions (RFC 1760)
+otputil_skey_code
 otputil_skey_dict_value
 otputil_skey_dict_word
+otputil_skey_str
 #
 # TOTP functions (RFC 6238)
 otputil_totp_code
diff --git a/lib/libotputil/lrfc1760-skey.c b/lib/libotputil/lrfc1760-skey.c
index 62e5d5e..1853455 100644
--- a/lib/libotputil/lrfc1760-skey.c
+++ b/lib/libotputil/lrfc1760-skey.c
@@ -43,6 +43,8 @@
 #include <errno.h>
 #include <string.h>
 #include <strings.h>
+#include <openssl/evp.h>
+#include <openssl/hmac.h>
 
 #include "lrfc1760-skey-dict.h"
 
@@ -136,4 +138,89 @@ otputil_skey_dict_word(
 }
 
 
+//---------------//
+// OTP functions //
+//---------------//
+#pragma mark OTP functions
+
+int
+otputil_skey_code(
+         const char *                  skey_pass,
+         int                           skey_seq,
+         uint64_t *                    skey_resultp )
+{
+   unsigned char     secret[OTPUTIL_SKEY_PASS_MAX_LEN+1];
+   const EVP_MD *    evp_md;
+   unsigned char     md[EVP_MAX_MD_SIZE];
+   unsigned          md_len;
+   unsigned          secret_len;
+   unsigned          u;
+   int               pos;
+
+   assert(skey_pass != NULL);
+
+   // generate secret
+   secret_len = (int)strlen(skey_pass);
+   if (secret_len > OTPUTIL_SKEY_PASS_MAX_LEN)
+      return(-1);
+   bindle_strlcpy((char *)secret, skey_pass, sizeof(secret));
+
+   // check otp_hash
+   evp_md = EVP_md4();
+
+   // generate hashes
+   for(pos = 0; (pos <= skey_seq); pos++)
+   {
+      md_len = sizeof(md);
+      if (!(EVP_Digest(secret, secret_len, md, &md_len, evp_md, NULL)))
+         return(-1);
+      for(u = 0; (u < 8); u++)
+         md[u] ^= md[u+8];
+      memcpy(secret, md, 8);
+      secret_len = 8;
+   };
+
+   *skey_resultp  = ((uint64_t)secret[0] << 56) | ((uint64_t)secret[1] << 48)
+                  | ((uint64_t)secret[2] << 40) | ((uint64_t)secret[3] << 32)
+                  | ((uint64_t)secret[4] << 24) | ((uint64_t)secret[5] << 16)
+                  | ((uint64_t)secret[6] <<  8) | ((uint64_t)secret[7] <<  0);
+
+   return(0);
+}
+
+
+char *
+otputil_skey_str(
+         const char *                  skey_pass,
+         int                           skey_seq,
+         char *                        dst,
+         size_t                        dstlen )
+{
+   uint64_t          val;
+   otputil_bv_t      res;
+   uint8_t           bv_val[8];
+   static char       buff[32];
+
+   dstlen      = ((dst))         ? dstlen       : sizeof(buff);
+   dst         = ((dst))         ? dst          : buff;
+   res.bv_val  = bv_val;
+   res.bv_len  = sizeof(bv_val);
+
+   if (otputil_skey_code(skey_pass, skey_seq, &val) == -1)
+      return(NULL);
+
+   bv_val[0] = (val >> 56) & 0xff;
+   bv_val[1] = (val >> 48) & 0xff;
+   bv_val[2] = (val >> 40) & 0xff;
+   bv_val[3] = (val >> 32) & 0xff;
+   bv_val[4] = (val >> 24) & 0xff;
+   bv_val[5] = (val >> 16) & 0xff;
+   bv_val[6] = (val >>  8) & 0xff;
+   bv_val[7] = (val >>  0) & 0xff;
+   otputil_otp_encode(&res, dst, dstlen, OTPUTIL_ENC_SIXWORD);
+
+   return(dst);
+}
+
+
 /* end of source file */