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fix: Fix length field implementation in gcm_crack

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Length field was calculated after padding
This commit is contained in:
Alivecow 2024-12-03 23:15:42 +01:00
parent 555ee45aad
commit 90d61a655e
1 changed files with 3 additions and 1 deletions
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4
src/tasks/tasks01/gcm_crack.rs
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@ -35,9 +35,12 @@ struct Message {
fn parse_message(val: &Value) -> Result<(Message, Polynomial)> { fn parse_message(val: &Value) -> Result<(Message, Polynomial)> {
let ciphertext_text: String = serde_json::from_value(val["ciphertext"].clone())?; let ciphertext_text: String = serde_json::from_value(val["ciphertext"].clone())?;
let mut ciphertext_bytes: Vec<u8> = BASE64_STANDARD.decode(ciphertext_text)?; let mut ciphertext_bytes: Vec<u8> = BASE64_STANDARD.decode(ciphertext_text)?;
let mut c_len: Vec<u8> = ((ciphertext_bytes.len() * 8) as u64).to_be_bytes().to_vec();
if ciphertext_bytes.len() % 16 != 0 { if ciphertext_bytes.len() % 16 != 0 {
ciphertext_bytes.append(vec![0u8; 16 - (ciphertext_bytes.len() % 16)].as_mut()); ciphertext_bytes.append(vec![0u8; 16 - (ciphertext_bytes.len() % 16)].as_mut());
} }
let ciphertext_chunks: Vec<FieldElement> = ciphertext_bytes let ciphertext_chunks: Vec<FieldElement> = ciphertext_bytes
.chunks(16) .chunks(16)
.into_iter() .into_iter()
@ -61,7 +64,6 @@ fn parse_message(val: &Value) -> Result<(Message, Polynomial)> {
let tag_bytes: Vec<u8> = BASE64_STANDARD.decode(tag_text)?; let tag_bytes: Vec<u8> = BASE64_STANDARD.decode(tag_text)?;
let tag_field: FieldElement = FieldElement::new(tag_bytes.clone()); let tag_field: FieldElement = FieldElement::new(tag_bytes.clone());
let mut c_len: Vec<u8> = ((ciphertext_bytes.len() * 8) as u64).to_be_bytes().to_vec();
l_field.append(c_len.as_mut()); l_field.append(c_len.as_mut());
// Combine all data // Combine all data