add check that pkcs #1 v1.5 is greater then 8 bytes

Author: NegaScout

docs/src/examples.md

@@ -7,7 +7,7 @@ Random.seed!(42)
 private_key, public_key = ToyPublicKeys.generate_rsa_key_pair(2048)
 msg = "Super secret message!"
 println(msg)
-encrypted = ToyPublicKeys.encrypt(msg, public_key; pad_length = 1)
+encrypted = ToyPublicKeys.encrypt(msg, public_key)
 println(encrypted)
 decrypted = ToyPublicKeys.decrypt(encrypted, private_key)
 println(decrypted)

src/padding/pkcs_1_v1_5.jl

@@ -25,6 +25,7 @@ end
 Core implementation of the [PKCS#1 v1.5 padding](https://www.rfc-editor.org/rfc/rfc2313#section-8.1).
 """
 function pad(msg::AbstractVector{T}, pad_length=32) where {T<:Base.BitInteger}
+    pad_length > 8 || throw(error("Will not create pad with length < 8"))
     buff = rand(T(1):T(typemax(T)), pad_length + 3)
     buff[1] = 0
     buff[2] = 2
@@ -39,6 +40,7 @@ end
 Wrapper for the core pad function.
 """
 function pad(msg::T, pad_length=32) where {T<:AbstractString}
+    pad_length > 8 || throw(error("Will not create pad with length < 8"))
     msg_cu = codeunits(msg)
     msg_padded = pad(msg_cu, pad_length)
     return T(msg_padded)

test/rsa.jl

@@ -59,22 +59,11 @@ end
     @test msg == decrypted
 end
 
-@testset "padding/pkcs_1_v1_5" begin
-    test_vector = Vector{UInt8}([1,2,3])
-    Random.seed!(42)
-    padded_vector_correct = UInt8[0x00, 0x02, 0x7a, 0xb4, 0xac, 0x2b, 0x9d, 0xab, 0x75, 0x4d, 0xa9, 0xa4, 0x58, 0x45, 0x84, 0x17, 0x46, 0x31, 0x6d, 0x7c, 0x15, 0x84, 0x33, 0x9a, 0x66, 0x51, 0x6f, 0xdb, 0x52, 0x90, 0x53, 0x29, 0xb9, 0x5f, 0x00, 0x01, 0x02, 0x03]
-    padded_vec = ToyPublicKeys.pad(test_vector)
-    @test padded_vector_correct == padded_vec
-    unpadded_vector = ToyPublicKeys.unpad(padded_vector_correct)
-    @test test_vector == unpadded_vector
-    @test UInt8[0x00, 0x02, 0x00, 0x01, 0x02, 0x03] == ToyPublicKeys.pad(test_vector, 0)
-end
-
 @testset "Decryption(Encryption) is identity ~ CodeUnits" begin
     Random.seed!(42)
     private_key, public_key = ToyPublicKeys.generate_rsa_key_pair(2048)
     msg = Base.CodeUnits("1")
-    encrypted = ToyPublicKeys.encrypt(msg, public_key; pad_length = 1)
+    encrypted = ToyPublicKeys.encrypt(msg, public_key)
     decrypted = ToyPublicKeys.decrypt(encrypted, private_key)
     @test decrypted == msg
 end
@@ -83,7 +72,7 @@ end
     Random.seed!(42)
     private_key, public_key = ToyPublicKeys.generate_rsa_key_pair(2048)
     msg = "1"
-    encrypted = ToyPublicKeys.encrypt(msg, public_key; pad_length = 1)
+    encrypted = ToyPublicKeys.encrypt(msg, public_key)
     decrypted = ToyPublicKeys.decrypt(encrypted, private_key)
     @test decrypted == msg
 end
@@ -92,6 +81,6 @@ end
     Random.seed!(42)
     private_key, public_key = ToyPublicKeys.generate_rsa_key_pair(2048)
     msg = "1"
-    signature = ToyPublicKeys.sign(msg, private_key; pad_length = 1)
+    signature = ToyPublicKeys.sign(msg, private_key)
     @test ToyPublicKeys.verify_signature(msg, signature, public_key)
 end