2 files changed, 118 insertions, 0 deletions
diff --git a/src/xor/xoroshiro256_prng.c b/src/xor/xoroshiro256_prng.c
new file mode 100644
index 0000000..defef88
--- /dev/null
+++ b/src/xor/xoroshiro256_prng.c
@@ -0,0 +1,74 @@
+/*
+ * XORoshiro-256 PRNG Implementation
+ * Author: Fabian Druschke
+ * Date: 2024-03-13
+ *
+ * This is a XORoshiro-256 (XOR/rotate/shift/rotate) pseudorandom number generator
+ * implementation, designed for fast and efficient generation of high-quality
+ * pseudorandom numbers. XORoshiro-256 is part of the XORoshiro family of PRNGs known
+ * for their simplicity and excellent statistical properties for a wide range of
+ * applications, though they are not suitable for cryptographic purposes due to their
+ * predictability.
+ *
+ * As the author of this implementation, I, Fabian Druschke, hereby release this work into
+ * the public domain. I dedicate any and all copyright interest in this work to the public
+ * domain, making it free to use for anyone for any purpose without any conditions, unless
+ * such conditions are required by law.
+ *
+ * This software is provided "as is", without warranty of any kind, express or implied,
+ * including but not limited to the warranties of merchantability, fitness for a particular
+ * purpose, and noninfringement. In no event shall the authors be liable for any claim,
+ * damages, or other liability, whether in an action of contract, tort, or otherwise, arising
+ * from, out of, or in connection with the software or the use or other dealings in the software.
+ *
+ * Note: This implementation does not utilize OpenSSL or any cryptographic libraries, as
+ * XORoshiro-256 is not intended for cryptographic applications. It is crucial for applications
+ * requiring cryptographic security to use a cryptographically secure PRNG.
+ */
+
+#include "xoroshiro256_prng.h"
+#include <stdint.h>
+#include <string.h>
+
+void xoroshiro256_init( xoroshiro256_state_t* state, uint64_t init_key[], unsigned long key_length )
+{
+    // Initialization logic; ensure 256 bits are properly seeded
+    for( int i = 0; i < 4; i++ )
+    {
+        if( i < key_length )
+        {
+            state->s[i] = init_key[i];
+        }
+        else
+        {
+            // Example fallback for insufficient seeds; consider better seeding strategies
+            state->s[i] = state->s[i - 1] * 6364136223846793005ULL + 1;
+        }
+    }
+}
+
+static inline uint64_t rotl( const uint64_t x, int k )
+{
+    return ( x << k ) | ( x >> ( 64 - k ) );
+}
+
+void xoroshiro256_genrand_uint256_to_buf( xoroshiro256_state_t* state, unsigned char* bufpos )
+{
+    // This part of the code updates the state using xoroshiro256**'s algorithm.
+    const uint64_t result_starstar = rotl( state->s[1] * 5, 7 ) * 9;
+    const uint64_t t = state->s[1] << 17;
+
+    state->s[2] ^= state->s[0];
+    state->s[3] ^= state->s[1];
+    state->s[1] ^= state->s[2];
+    state->s[0] ^= state->s[3];
+
+    state->s[2] ^= t;
+    state->s[3] = rotl( state->s[3], 45 );
+
+    // Note: 'result_starstar' was only used for demonstration purposes and is not part of the
+    // original Xoroshiro256** specification. Here, we write the complete state into the buffer.
+    // Ensure that 'bufpos' has enough storage space (256 bits / 32 bytes).
+
+    memcpy( bufpos, state->s, 32 );  // Copies the entire 256-bit (32 bytes) state into 'bufpos'
+}
diff --git a/src/xor/xoroshiro256_prng.h b/src/xor/xoroshiro256_prng.h
new file mode 100644
index 0000000..a7d9232
--- /dev/null
+++ b/src/xor/xoroshiro256_prng.h
@@ -0,0 +1,44 @@
+/*
+ * XORoshiro-256 PRNG Definitions
+ * Author: Fabian Druschke
+ * Date: 2024-03-13
+ *
+ * This header file contains definitions for the XORoshiro-256 pseudorandom number generator
+ * (PRNG) implementation. XORoshiro-256 is part of the XORoshiro family of PRNGs, known for
+ * their simplicity, efficiency, and high-quality pseudorandom number generation suitable for
+ * a wide range of applications, excluding cryptographic purposes due to its predictable nature.
+ *
+ * As the author of this work, I, Fabian Druschke, hereby release this work into the public
+ * domain. I dedicate any and all copyright interest in this work to the public domain, making
+ * it free to use for anyone for any purpose without any conditions, unless such conditions are
+ * required by law.
+ *
+ * This software is provided "as is", without warranty of any kind, express or implied,
+ * including but not limited to the warranties of merchantability, fitness for a particular
+ * purpose, and noninfringement. In no event shall the authors be liable for any claim,
+ * damages, or other liability, whether in an action of contract, tort, or otherwise, arising
+ * from, out of, or in connection with the software or the use or other dealings in the software.
+ *
+ * Note: This implementation does not utilize any cryptographic libraries, as XORoshiro-256 is
+ * not intended for cryptographic applications. It is crucial for applications requiring
+ * cryptographic security to use a cryptographically secure PRNG.
+ */
+
+#ifndef XOROSHIRO256_PRNG_H
+#define XOROSHIRO256_PRNG_H
+
+#include <stdint.h>
+
+// Structure to store the state of the xoroshiro256** random number generator
+typedef struct xoroshiro256_state_s
+{
+    uint64_t s[4];
+} xoroshiro256_state_t;
+
+// Initializes the xoroshiro256** random number generator with a seed
+void xoroshiro256_init( xoroshiro256_state_t* state, uint64_t init_key[], unsigned long key_length );
+
+// Generates a 256-bit random number using xoroshiro256** and stores it directly in the output buffer
+void xoroshiro256_genrand_uint256_to_buf( xoroshiro256_state_t* state, unsigned char* bufpos );
+
+#endif  // XOROSHIRO256_PRNG_H