1 files changed, 91 insertions, 0 deletions
diff --git a/crypto_scrypt-check.c b/crypto_scrypt-check.c
new file mode 100644
index 0000000..1aaa88a
--- /dev/null
+++ b/crypto_scrypt-check.c
@@ -0,0 +1,91 @@
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <math.h>
+
+#include "libscrypt.h"
+
+/* pow() works with doubles. Sounds like it should cast to int correctly,
+* but doesn't always. This is faster anyway
+*/
+static uint16_t ipow(uint16_t base, uint32_t exp)
+{
+    uint16_t result = 1;
+    while (exp != 0)
+    {
+        if ((exp & 1) != 0)
+            result *= base;
+        exp >>= 1;
+        base *= base;
+    }
+
+    return result;
+}
+
+int libscrypt_check(char *mcf, char *password)
+{
+
+	uint32_t params;
+	uint16_t N;
+	uint8_t r, p;
+	int retval;
+	uint8_t hashbuf[64];
+	char outbuf[128];
+	char salt[32];
+	char *tok;
+
+	if(memcmp(mcf, SCRYPT_MCF_ID, 3) != 0)
+	{
+		/* Only version 0 supported */
+		return -1;
+	}
+
+	tok = strtok(mcf, "$");
+	tok = strtok(NULL, "$");
+
+	if ( !tok )
+		return -1;
+
+	params = (uint32_t)strtoul(tok, NULL, 16);
+	if ( params == 0 )
+		return -1;
+
+	tok = strtok(NULL, "$");
+
+	if ( !tok )
+		return -1;
+
+	p = params & 0xff;
+	r = (params >> 8) & 0xff;
+	N = params >> 16;
+	N = ipow(2, N);
+
+	/* Useful debugging:
+	printf("We've obtained salt 'N' r p of '%s' %d %d %d\n", tok, N,r,p);
+	*/
+
+	retval = libscrypt_b64_decode(salt, tok, strlen(tok));
+	if (retval < 1)
+		return -1;
+	retval = libscrypt_scrypt((uint8_t*)password,strlen(password), (uint8_t*)salt, (uint32_t)retval, N, r, p, hashbuf, sizeof(hashbuf));
+
+	if (retval != 0)
+		return retval;
+
+	retval = libscrypt_b64_encode(outbuf, (char*)hashbuf, sizeof(hashbuf));
+	if (retval == 0)
+		return -1;
+
+	tok = strtok(NULL, "$");
+
+	if ( !tok )
+		return -1;
+
+	if(strcmp(tok, outbuf) == 0)
+	{
+		return 1;
+	}
+
+	return 0;
+}
+