Remco Bloemen
A fine-tuned implementation of the SHA256 hashing algorithm.
Dependents: EntropySource Wallet_v1
SHA256.h@3:f19b10394f9c, 2011-06-20 (annotated)
- Committer:
- Remco
- Date:
- Mon Jun 20 11:00:20 2011 +0000
- Revision:
- 3:f19b10394f9c
- Parent:
- 2:1991439ea6b8
- Child:
- 4:81678751d669
Who changed what in which revision?
| User | Revision | Line number | New contents of line |
|---|---|---|---|
| Remco | 0:772b6de3a841 | 1 | // Author: Remco Bloemen |
| Remco | 0:772b6de3a841 | 2 | // Based on: |
| Remco | 0:772b6de3a841 | 3 | // http://en.wikipedia.org/wiki/SHA-2 |
| Remco | 0:772b6de3a841 | 4 | // http://www.iwar.org.uk/comsec/resources/cipher/sha256-384-512.pdf |
| Remco | 3:f19b10394f9c | 5 | // OpenSSL optimizations |
| Remco | 0:772b6de3a841 | 6 | |
| Remco | 3:f19b10394f9c | 7 | #pragma once |
| Remco | 0:772b6de3a841 | 8 | #include <string.h> |
| Remco | 0:772b6de3a841 | 9 | #include <string> |
| Remco | 0:772b6de3a841 | 10 | |
| Remco | 3:f19b10394f9c | 11 | /// Class to quickly compute SHA-256 hashes |
| Remco | 3:f19b10394f9c | 12 | /// |
| Remco | 3:f19b10394f9c | 13 | /// This class has been heavily optimized for speed |
| Remco | 3:f19b10394f9c | 14 | /// at a slight expense of code size. |
| Remco | 0:772b6de3a841 | 15 | class SHA256 { |
| Remco | 0:772b6de3a841 | 16 | public: |
| Remco | 3:f19b10394f9c | 17 | //// Create a new instance, ready for appending |
| Remco | 0:772b6de3a841 | 18 | SHA256() { reset(); } |
| Remco | 3:f19b10394f9c | 19 | |
| Remco | 3:f19b10394f9c | 20 | /// Reset this instance so you can calculate a new hash |
| Remco | 0:772b6de3a841 | 21 | void reset(); |
| Remco | 3:f19b10394f9c | 22 | |
| Remco | 3:f19b10394f9c | 23 | /// Append data to the hash |
| Remco | 3:f19b10394f9c | 24 | /// |
| Remco | 3:f19b10394f9c | 25 | /// Note: due to word-allignment optimizations |
| Remco | 3:f19b10394f9c | 26 | /// the function may read up to three bytes beyond |
| Remco | 3:f19b10394f9c | 27 | /// the end of data. |
| Remco | 3:f19b10394f9c | 28 | /// |
| Remco | 3:f19b10394f9c | 29 | /// @param data The bytes to be added. |
| Remco | 3:f19b10394f9c | 30 | /// @param size The number of bytes to read from data, but see the note. |
| Remco | 0:772b6de3a841 | 31 | void append(const char* data, int size); |
| Remco | 3:f19b10394f9c | 32 | |
| Remco | 3:f19b10394f9c | 33 | /// Append a single byte. |
| Remco | 3:f19b10394f9c | 34 | /// Avoid this function if performance is important. |
| Remco | 3:f19b10394f9c | 35 | void append(char c) { append(&c, 1); } |
| Remco | 3:f19b10394f9c | 36 | |
| Remco | 3:f19b10394f9c | 37 | /// Append a zero terminated string |
| Remco | 3:f19b10394f9c | 38 | /// The terminating zero itself is not appended. |
| Remco | 0:772b6de3a841 | 39 | void append(const char* str) { append(str, strlen(str)); } |
| Remco | 3:f19b10394f9c | 40 | |
| Remco | 3:f19b10394f9c | 41 | /// Append a std::string |
| Remco | 0:772b6de3a841 | 42 | void append(const std::string& str) { append(str.data(), str.length()); } |
| Remco | 3:f19b10394f9c | 43 | |
| Remco | 3:f19b10394f9c | 44 | /// Append the required padding and compute the final digest |
| Remco | 3:f19b10394f9c | 45 | /// Always call this function first before requesting the digest |
| Remco | 3:f19b10394f9c | 46 | /// |
| Remco | 3:f19b10394f9c | 47 | /// After finalization you must call reset() before you can append again. |
| Remco | 3:f19b10394f9c | 48 | /// However, you can do this: |
| Remco | 3:f19b10394f9c | 49 | /// SHA256 hash1, hash1and2; |
| Remco | 3:f19b10394f9c | 50 | /// hash1.append("First part"); |
| Remco | 3:f19b10394f9c | 51 | /// hash1and2 = hash1; |
| Remco | 3:f19b10394f9c | 52 | /// hash1.finalize(); |
| Remco | 3:f19b10394f9c | 53 | /// hash1and2.append("Second part"); |
| Remco | 3:f19b10394f9c | 54 | /// hash1and2.finalize(); |
| Remco | 0:772b6de3a841 | 55 | void finalize(); |
| Remco | 3:f19b10394f9c | 56 | |
| Remco | 3:f19b10394f9c | 57 | /// Returns a pointer to the 32 bytes of the digest |
| Remco | 0:772b6de3a841 | 58 | const char* digest() { return reinterpret_cast<char*>(hash); } |
| Remco | 3:f19b10394f9c | 59 | |
| Remco | 3:f19b10394f9c | 60 | /// Return the digest as a binary std::string |
| Remco | 3:f19b10394f9c | 61 | /// |
| Remco | 3:f19b10394f9c | 62 | /// Avoid this function if performance is important, |
| Remco | 3:f19b10394f9c | 63 | /// the std::string constructor will make a copy of the |
| Remco | 3:f19b10394f9c | 64 | /// digest internally, doing a malloc and memcpy. |
| Remco | 3:f19b10394f9c | 65 | std::string binString() { return std::string(digest(), 32); } |
| Remco | 3:f19b10394f9c | 66 | |
| Remco | 3:f19b10394f9c | 67 | /// Return the digest as a hexadecimal std::string |
| Remco | 3:f19b10394f9c | 68 | /// |
| Remco | 3:f19b10394f9c | 69 | /// In addition to the note for binaryString, this function |
| Remco | 3:f19b10394f9c | 70 | /// also does conversion. |
| Remco | 3:f19b10394f9c | 71 | std::string hexString(); |
| Remco | 3:f19b10394f9c | 72 | |
| Remco | 0:772b6de3a841 | 73 | private: |
| Remco | 0:772b6de3a841 | 74 | void process_chunk(); |
| Remco | 0:772b6de3a841 | 75 | int length; |
| Remco | 0:772b6de3a841 | 76 | unsigned int hash[8]; |
| Remco | 2:1991439ea6b8 | 77 | unsigned int w[16]; |
| Remco | 0:772b6de3a841 | 78 | }; |
| Remco | 0:772b6de3a841 | 79 |