CBP - Certified Bitcoin Professional Fundamental Cryptography Concepts Questions and Answers 1 — Questions and Answers
Question 1: In the context of Bitcoin's public-key cryptography, which of the following statements accurately describes the relationship between a private key, a public key, and a Bitcoin address?
- A Bitcoin address is a hashed version of the public key, which is mathematically derived from the private key. (Correct answer)
- A public key is a hashed version of the Bitcoin address, which is mathematically derived from the private key.
- A private key is a hashed version of the public key, which is used to generate a Bitcoin address.
- A Bitcoin address and a public key are identical, and both are derived from the private key.
Correct answer: A Bitcoin address is a hashed version of the public key, which is mathematically derived from the private key.
The foundational principle of Bitcoin's cryptography is that a private key is generated first. From this private key, a corresponding public key is derived using Elliptic Curve Cryptography. The public key is then put through hashing algorithms (SHA-256 and RIPEMD-160) to produce the public Bitcoin address that is shared to receive funds.
Question 2: A user wants to send a Bitcoin transaction. To prove they are the legitimate owner of the funds, they must create a digital signature. Which cryptographic component is used to create this signature?
- The recipient's public key
- The user's private key (Correct answer)
- The transaction hash
- The user's public key
Correct answer: The user's private key
A digital signature in Bitcoin is created by signing the hash of the transaction data with the sender's private key. This proves ownership of the funds being spent without revealing the private key itself. Others on the network can then use the sender's public key to verify that the signature is valid.
Question 3: Which characteristic of a cryptographic hash function is most critical for ensuring the immutability of the Bitcoin blockchain?
- Fast computation
- Fixed-size output
- Pre-image resistance (Correct answer)
- Collision resistance
Correct answer: Pre-image resistance
Pre-image resistance means it is computationally infeasible to find an input that hashes to a specific output. For the blockchain, this means it's practically impossible to alter a block's data without changing its hash. Since each block's hash is included in the subsequent block, changing a historical block would require re-mining that block and all subsequent blocks, which is computationally infeasible. This property directly contributes to the blockchain's immutability.
Question 4: A Bitcoin user has a 12-word mnemonic seed phrase. What is the primary function of this phrase in relation to cryptographic keys?
- It is a human-readable representation of the user's public key.
- It directly encrypts the transaction data on the blockchain.
- It serves as a symmetric key to decrypt incoming Bitcoin.
- It is used to deterministically generate all private keys in a hierarchical deterministic (HD) wallet. (Correct answer)
Correct answer: It is used to deterministically generate all private keys in a hierarchical deterministic (HD) wallet.
A mnemonic seed phrase, as defined by standards like BIP39, is a backup mechanism. It is used as a seed to a deterministic algorithm that can recreate the master private key, and from there, all the public/private key pairs within the wallet. This allows a user to restore their entire wallet on a new device with just the seed phrase.
Question 5: In asymmetric cryptography (also known as public-key cryptography), which key is kept secret and which is shared?
- Both the public and private keys are kept secret.
- The public key is kept secret, and the private key is shared.
- Both the public and private keys are shared.
- The private key is kept secret, and the public key is shared. (Correct answer)
Correct answer: The private key is kept secret, and the public key is shared.
The core principle of asymmetric cryptography is the use of a key pair: a private key, which must be kept secret by the owner, and a public key, which can be freely distributed. Data encrypted with the public key can only be decrypted by the corresponding private key, and a signature created with the private key can be verified with the public key.
Question 6: Bitcoin's Proof of Work algorithm primarily uses the SHA-256 cryptographic hash function. What is the result of applying the SHA-256 function to a block's header data?
- A 512-bit hash value.
- A 256-bit hash value. (Correct answer)
- The private key for the next block.
- A variable-length string of characters.
Correct answer: A 256-bit hash value.
The SHA-256 algorithm always produces a fixed-size output of 256 bits (or 32 bytes), regardless of the size of the input data. In Bitcoin mining, miners repeatedly hash the block header, changing a nonce, until they find a hash that is below the current difficulty target. This resulting hash is 256 bits long.
CBP - Certified Bitcoin Professional Fundamental Cryptography Concepts Questions and Answers 1
In the context of Bitcoin's public-key cryptography, which of the following statements accurately describes the relationship between a private key, a public key, and a Bitcoin address?