open System.IO
open System.Security.Cryptography
-// Some cryptography primitives specific to CryptoFile.
+// Some cryptography primitives specific to 'CryptoFile'.
module internal Crypto =
type Data = byte[]
- let rsaKeySize = 2048
+ let rsaKeySize = 3072 // [bit]. For encrypting and signing.
+ let aesKeySize = 128 // [bit].
- /// Returns a cryptographically strong sequence of bytes.
+ exception KeySizeError
+ exception IVSizeError
+
+ /// Return a cryptographically strong sequence of bytes.
let rand size : byte[] =
let result = Array.zeroCreate size
- let generator = new RNGCryptoServiceProvider ()
+ use generator = new RNGCryptoServiceProvider ()
generator.GetBytes result
result
/// Generate a new RSA key pair: (public * private).
- let generateRSAKeysPair : Key * Key =
+ let generateRSAKeysPair () : Key * Key =
use rsa = new RSACryptoServiceProvider (rsaKeySize)
- try
- rsa.ToXmlString false, rsa.ToXmlString true
- finally
- rsa.PersistKeyInCsp <- false
+ rsa.ToXmlString false, rsa.ToXmlString true
let encryptRSA (publicKey: Key) (plaindata: Data) : Data =
use rsa = new RSACryptoServiceProvider (rsaKeySize)
- try
- rsa.FromXmlString publicKey
- rsa.Encrypt (plaindata, false) // Uses PKCS#1 v1.5 padding.
- finally
- rsa.PersistKeyInCsp <- false
+ rsa.FromXmlString publicKey
+ rsa.Encrypt (plaindata, true) // Use padding OAEP (PKCS#1 v2).
let decryptRSA (privateKey: Key) (cipherdata: Data) : Data =
use rsa = new RSACryptoServiceProvider (rsaKeySize)
- try
- rsa.FromXmlString privateKey
- rsa.Decrypt (cipherdata, false) // Uses PKCS#1 v1.5 padding.
- finally
- rsa.PersistKeyInCsp <- false
+ rsa.FromXmlString privateKey
+ rsa.Decrypt (cipherdata, true) // Use padding OAEP (PKCS#1 v2).
- /// Produces a signature from a given hash.
- let signRSA (privKey: Key) (sha256: Data) : Data =
+ /// Produce a signature from the given data.
+ let signRSA (privKey: Key) (data: Data) : Data =
use rsa = new RSACryptoServiceProvider (rsaKeySize)
- try
- rsa.FromXmlString privKey
- rsa.SignHash (sha256, CryptoConfig.MapNameToOID "SHA256")
- finally
- rsa.PersistKeyInCsp <- false
+ rsa.FromXmlString privKey
+ rsa.SignHash (data, CryptoConfig.MapNameToOID "SHA256")
- /// Verify a signature against a given hash.
- let verifySignRSA (pubKey: Key) (sha256: Data) (signature: Data) : bool =
+ /// Verify a signature against the given data.
+ let verifySignRSA (pubKey: Key) (data: Data) (signature: Data) : bool =
use rsa = new RSACryptoServiceProvider (rsaKeySize)
- try
- rsa.FromXmlString pubKey
- rsa.VerifyHash (sha256, CryptoConfig.MapNameToOID "SHA256", signature)
- finally
- rsa.PersistKeyInCsp <- false
+ rsa.FromXmlString pubKey
+ rsa.VerifyHash (data, CryptoConfig.MapNameToOID "SHA256", signature)
- /// Returns an encrypted output stream.
+ /// Return an encrypted output stream.
let encryptAES (key: byte[]) (iv: byte[]) (outputStream: Stream) : CryptoStream =
- assert (key.Length = 32 && iv.Length = 16)
- use aes = new AesManaged ()
- aes.KeySize <- 256
- let encryptor = aes.CreateEncryptor (key, iv)
- new CryptoStream (outputStream, encryptor, CryptoStreamMode.Write)
+ if key.Length <> aesKeySize / 8 then raise KeySizeError
+ if iv.Length <> 16 then raise IVSizeError
+ use aes = new AesCryptoServiceProvider (KeySize = aesKeySize) // Default mode is CBC.
+ new CryptoStream (outputStream, aes.CreateEncryptor (key, iv), CryptoStreamMode.Write)
- /// Returns a decrypted input stream.
+ /// Return a decrypted input stream.
let decryptAES (key: byte[]) (iv: byte[]) (inputStream: Stream) : CryptoStream =
- assert (key.Length = 32 && iv.Length = 16)
- use aes = new AesManaged ()
- aes.KeySize <- 256
- let decryptor = aes.CreateDecryptor (key, iv)
- new CryptoStream (inputStream, decryptor, CryptoStreamMode.Read)
+ if key.Length <> aesKeySize / 8 then raise KeySizeError
+ if iv.Length <> 16 then raise IVSizeError
+ use aes = new AesCryptoServiceProvider (KeySize = aesKeySize)
+ new CryptoStream (inputStream, aes.CreateDecryptor (key, iv), CryptoStreamMode.Read)
- // Create a stream to compute the HMAC-SHA256 against all data being written.
+ /// Create a stream to compute HMAC-SHA256 against all data being written.
let HMACStream (key: byte[]) (outputStream: Stream) : Stream * HMACSHA256 =
- assert (key.Length = 32)
+ if key.Length <> 32 then raise KeySizeError
let hmac = new HMACSHA256 (key)
new CryptoStream (outputStream, hmac, CryptoStreamMode.Write) :> Stream, hmac
+ /// Compute HMAC-SHA256 for all the data in the input stream.
let ComputeHMAC (key: byte[]) (inputStream: Stream) : byte[] =
- assert (key.Length = 32)
- let hmac = new HMACSHA256 (key)
+ if key.Length <> 32 then raise KeySizeError
+ use hmac = new HMACSHA256 (key)
hmac.ComputeHash inputStream
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