iOS Reverse cryptography

Cryptographic Science

1.HASH hashing (hash) function
Irreversible (cannot be used for encryption and decryption)
A binary data with only one hash value

2. Asymmetric RSA
Because it is a simple mathematical calculation, so the efficiency of encryption is low, generally used to encrypt the core (small data)

• Public key encryption, private key decryption
• Private key encryption, public key decryption

3. Symmetry

• Des
• 3DES

• Aes

  Openssl

  1. Generate the private key:

  openssl genrsa -out private.pem 521

  
  View:

  cat private.pem

  
  2. The public key is calculated from the private key:

  openssl rsa -in private.pem -out public.pem -pubout

  View:

  cat public.pem

  
  3. For easy viewing, you can output text:

  openssl rsa -in private.pem -text -out private.txt

Example: IOS CSR certificate (public key)

Keychain Request CSR certificate, view in Terminal:

cat CertificateSigningRequest.certSigningRequest

Displays a bunch of base64 encoded strings:

• More knowledge of cryptography can be self-Baidu
• Reference articles
• https://www.jianshu.com/p/d9cd97c77549
• https://www.jianshu.com/p/ad29445eb91c

iOS Reverse cryptography