diff --git a/src/libumskt/sha1/sha1.cpp b/src/libumskt/sha1/sha1.cpp
new file mode 100644
index 0000000..20e694b
--- /dev/null
+++ b/src/libumskt/sha1/sha1.cpp
@@ -0,0 +1,140 @@
+#include "sha1.h"
+#include <cstring>
+#include <bit>
+
+namespace umskt {
+
+// Rotate left operation
+static inline uint32_t rotl(uint32_t value, unsigned int bits) {
+    return (value << bits) | (value >> (32 - bits));
+}
+
+SHA1::SHA1() {
+    reset();
+}
+
+void SHA1::reset() {
+    std::memcpy(state, INIT_STATE, sizeof(state));
+    totalBytes = 0;
+    bufferSize = 0;
+}
+
+void SHA1::update(const uint8_t* data, size_t len) {
+    while (len > 0) {
+        size_t copy = std::min(BLOCK_SIZE - bufferSize, len);
+        std::memcpy(buffer + bufferSize, data, copy);
+        bufferSize += copy;
+        data += copy;
+        len -= copy;
+        
+        if (bufferSize == BLOCK_SIZE) {
+            processBlock(buffer);
+            totalBytes += BLOCK_SIZE;
+            bufferSize = 0;
+        }
+    }
+}
+
+SHA1::Digest SHA1::finalize() {
+    // Total size including padding must be a multiple of 64 bytes
+    totalBytes += bufferSize;
+    
+    // Add padding byte
+    buffer[bufferSize++] = 0x80;
+    
+    // If there isn't enough room for the length (8 bytes), process this block and start a new one
+    if (bufferSize > BLOCK_SIZE - 8) {
+        std::memset(buffer + bufferSize, 0, BLOCK_SIZE - bufferSize);
+        processBlock(buffer);
+        bufferSize = 0;
+    }
+    
+    // Pad with zeros and add 64-bit length (in bits)
+    std::memset(buffer + bufferSize, 0, BLOCK_SIZE - 8 - bufferSize);
+    uint64_t bitCount = totalBytes * 8;
+    
+    // Store length in big-endian format
+    for (int i = 7; i >= 0; --i) {
+        buffer[BLOCK_SIZE - 1 - i] = static_cast<uint8_t>(bitCount >> (i * 8));
+    }
+    
+    processBlock(buffer);
+    
+    // Convert state to bytes (big-endian)
+    Digest digest;
+    for (int i = 0; i < 5; ++i) {
+        digest[i*4] = static_cast<uint8_t>(state[i] >> 24);
+        digest[i*4 + 1] = static_cast<uint8_t>(state[i] >> 16);
+        digest[i*4 + 2] = static_cast<uint8_t>(state[i] >> 8);
+        digest[i*4 + 3] = static_cast<uint8_t>(state[i]);
+    }
+    
+    return digest;
+}
+
+void SHA1::processBlock(const uint8_t* block) {
+    // Convert block to 16 32-bit words (big-endian)
+    uint32_t w[80];
+    for (int i = 0; i < 16; ++i) {
+        w[i] = (static_cast<uint32_t>(block[i*4]) << 24) |
+               (static_cast<uint32_t>(block[i*4 + 1]) << 16) |
+               (static_cast<uint32_t>(block[i*4 + 2]) << 8) |
+               static_cast<uint32_t>(block[i*4 + 3]);
+    }
+    
+    // Extend 16 words to 80 words
+    for (int i = 16; i < 80; ++i) {
+        w[i] = rotl(w[i-3] ^ w[i-8] ^ w[i-14] ^ w[i-16], 1);
+    }
+    
+    // Initialize working variables
+    uint32_t a = state[0];
+    uint32_t b = state[1];
+    uint32_t c = state[2];
+    uint32_t d = state[3];
+    uint32_t e = state[4];
+    
+    // Main loop
+    for (int i = 0; i < 80; ++i) {
+        uint32_t f, k;
+        
+        if (i < 20) {
+            f = (b & c) | ((~b) & d);
+            k = 0x5A827999;
+        }
+        else if (i < 40) {
+            f = b ^ c ^ d;
+            k = 0x6ED9EBA1;
+        }
+        else if (i < 60) {
+            f = (b & c) | (b & d) | (c & d);
+            k = 0x8F1BBCDC;
+        }
+        else {
+            f = b ^ c ^ d;
+            k = 0xCA62C1D6;
+        }
+        
+        uint32_t temp = rotl(a, 5) + f + e + k + w[i];
+        e = d;
+        d = c;
+        c = rotl(b, 30);
+        b = a;
+        a = temp;
+    }
+    
+    // Update state
+    state[0] += a;
+    state[1] += b;
+    state[2] += c;
+    state[3] += d;
+    state[4] += e;
+}
+
+SHA1::Digest SHA1::hash(const uint8_t* data, size_t len) {
+    SHA1 sha1;
+    sha1.update(data, len);
+    return sha1.finalize();
+}
+
+} // namespace umskt 
\ No newline at end of file
diff --git a/src/libumskt/sha1/sha1.h b/src/libumskt/sha1/sha1.h
new file mode 100644
index 0000000..72c9b20
--- /dev/null
+++ b/src/libumskt/sha1/sha1.h
@@ -0,0 +1,59 @@
+#ifndef UMSKT_SHA1_H
+#define UMSKT_SHA1_H
+
+#include "../../typedefs.h"
+#include <cstdint>
+#include <array>
+#include <string>
+
+// OpenSSL-compatible constants
+#define SHA_DIGEST_LENGTH 20
+#define SHA_CBLOCK    64
+#define SHA_LBLOCK    16
+
+namespace umskt {
+
+class SHA1 {
+public:
+    static constexpr size_t DIGEST_SIZE = SHA_DIGEST_LENGTH;  // SHA1 produces a 160-bit (20-byte) hash
+    using Digest = std::array<uint8_t, DIGEST_SIZE>;
+
+    SHA1();
+    
+    // Update the hash with more data
+    void update(const uint8_t* data, size_t len);
+    
+    // Finalize and get the hash
+    Digest finalize();
+    
+    // Reset the hash state
+    void reset();
+    
+    // Convenience method to hash data in one call
+    static Digest hash(const uint8_t* data, size_t len);
+
+private:
+    static constexpr size_t BLOCK_SIZE = SHA_CBLOCK;  // SHA1 operates on 512-bit (64-byte) blocks
+    static constexpr uint32_t INIT_STATE[5] = {
+        0x67452301, 0xEFCDAB89, 0x98BADCFE, 0x10325476, 0xC3D2E1F0
+    };
+
+    void processBlock(const uint8_t* block);
+    
+    uint32_t state[5];           // Hash state
+    uint8_t buffer[BLOCK_SIZE];  // Input buffer
+    uint64_t totalBytes;         // Total bytes processed
+    size_t bufferSize;          // Current bytes in buffer
+};
+
+// OpenSSL-compatible function
+inline void SHA1_wrapper(const unsigned char* data, size_t len, unsigned char* digest) {
+    auto result = SHA1::hash(data, len);
+    std::copy(result.begin(), result.end(), digest);
+}
+
+} // namespace umskt
+
+#define SHA1_DIGEST(d,n,md) umskt::SHA1_wrapper((d),(n),(md))
+
+#endif // UMSKT_SHA1_H 
\ No newline at end of file