MD5 Hash Calculator

What is MD5?

MD5 (Message Digest Algorithm 5) is a widely used cryptographic hash function designed by Ronald Rivest in 1991. It can convert data of any length into a fixed-length hash value (128 bits, or 16 bytes).

MD5 Characteristics

• Fixed-length output: Regardless of input data length, MD5 always produces a 128-bit (16-byte) output
• Avalanche effect: Small changes in input cause significant changes in output
• One-way function: Original data cannot be derived from the hash value
• Collision resistance: Theoretically difficult to find two different inputs that produce the same hash value

MD5 Application Scenarios

1. Data integrity verification: Verify whether files have been tampered with during transmission
2. Password storage: Store hash values of user passwords (Note: modern applications recommend using more secure algorithms)
3. Digital signatures: As part of digital signature algorithms
4. File deduplication: Quickly identify duplicate files through hash values

MD5 Algorithm Principles

Algorithm Steps

1. Padding: Pad input data to multiples of 512 bits
2. Initialization: Set four 32-bit registers (A, B, C, D)
3. Main loop: Perform four rounds of processing, 16 steps each
4. Output: Concatenate the values of four registers into a 128-bit hash value

Mathematical Foundation

MD5 is based on the following mathematical operations:

• Modular arithmetic (mod 2^32)
• Bitwise operations (AND, OR, XOR, NOT)
• Circular left shift
• Non-linear functions (F, G, H, I)

Encoding Formats

Supported Encoding Formats

1. UTF-8: Most commonly used Unicode encoding format
2. ASCII: 7-bit character encoding
3. UTF-16: 16-bit Unicode encoding
4. UTF-32: 32-bit Unicode encoding
5. GBK: Chinese encoding format
6. ISO-8859-1: Western European language encoding

Output Formats

1. Lowercase hexadecimal: d41d8cd98f00b204e9800998ecf8427e
2. Uppercase hexadecimal: D41D8CD98F00B204E9800998ECF8427E
3. Base64: 1B2M2Y8AsgTpgAmY7PhCfg==

Last updated: January 20, 2024