base64

README

base64

-- import "github.com/go-i2p/common/base64"

Package base64 implements I2P-specific base64 encoding and decoding utilities.

This package provides base64 functionality tailored for the I2P (Invisible Internet Project) network, implementing a modified RFC 4648 base64 alphabet that ensures compatibility with I2P protocols and addressing schemes. The key modifications replace problematic characters: "/" becomes "~" to avoid filesystem conflicts, and "+" becomes "-" for URL-safe encoding without percent-encoding requirements.

The package is essential for handling I2P destination addresses, router identifiers, cryptographic key material, and binary data serialization throughout the I2P ecosystem. All encoding operations maintain standard base64 semantics while using the I2P-specific character set.

Usage patterns:

- Encoding binary data for I2P network transmission
- Generating .b64.i2p destination addresses
- Converting cryptographic keys to string representation
- Serializing router information and network database entries

The implementation emphasizes performance and thread safety, providing reusable encoder instances that can be safely used across concurrent operations without synchronization overhead.

Package base64 constants

Package base64 utilities and encoding instances

Usage

const I2PEncodeAlphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-~"

I2PEncodeAlphabet defines the I2P-specific base64 character set used throughout the network. This alphabet follows RFC 4648 standard base64 encoding with two critical modifications: - "/" is replaced with "~" to avoid filesystem path conflicts - "+" is replaced with "-" to ensure URL-safe encoding without percent-encoding The alphabet maintains the standard ordering: A-Z (0-25), a-z (26-51), 0-9 (52-61), - (62), ~ (63). This encoding is essential for I2P destination addresses, router identifiers, and network data structures. Example usage: Used in .b64.i2p addresses and binary data serialization across I2P protocols.

var I2PEncoding *b64.Encoding = b64.NewEncoding(I2PEncodeAlphabet)

I2PEncoding provides the standard base64 encoder/decoder instance for all I2P components. This encoding instance is pre-configured with the I2P-specific alphabet and optimizes performance by reusing the same encoder across multiple operations. It handles the complex character mapping required for I2P network compatibility while maintaining standard base64 semantics. The instance is thread-safe and can be used concurrently across goroutines. Example: Used internally by EncodeToString and DecodeString for consistent encoding behavior.

func DecodeString

func DecodeString(str string) ([]byte, error)

DecodeString converts I2P-compatible base64 strings back to their original binary form. This function reverses the encoding process, taking base64 strings that use I2P's alphabet and converting them back to the original byte data. It validates input characters against the I2P alphabet and handles standard base64 padding requirements. Returns an error if the input contains invalid characters or malformed padding. Example: DecodeString("SGVsbG8-") returns []byte{72, 101, 108, 108, 111}, nil (Hello decoded)

func EncodeToString

func EncodeToString(data []byte) string

EncodeToString converts arbitrary binary data to I2P-compatible base64 string representation. This function takes raw byte data and produces a human-readable string using I2P's modified base64 alphabet. The output is compatible with I2P destination addresses, router identifiers, and other network protocol elements that require base64 encoding. The encoding process applies standard base64 padding rules with '=' characters as needed. Example: EncodeToString([]byte{72, 101, 108, 108, 111}) returns "SGVsbG8-" (Hello in I2P base64)

base64

github.com/go-i2p/common/base64

go-i2p template file

Documentation

Overview

Package base64 implements I2P-specific base64 encoding and decoding utilities.

This package provides base64 functionality tailored for the I2P (Invisible Internet Project) network, implementing a modified RFC 4648 base64 alphabet that ensures compatibility with I2P protocols and addressing schemes. The key modifications replace problematic characters: "/" becomes "~" to avoid filesystem conflicts, and "+" becomes "-" for URL-safe encoding without percent-encoding requirements.

The package is essential for handling I2P destination addresses, router identifiers, cryptographic key material, and binary data serialization throughout the I2P ecosystem. All encoding operations maintain standard base64 semantics while using the I2P-specific character set.

Usage patterns:

• Encoding binary data for I2P network transmission
• Generating .b64.i2p destination addresses
• Converting cryptographic keys to string representation
• Serializing router information and network database entries

The implementation emphasizes performance and thread safety, providing reusable encoder instances that can be safely used across concurrent operations without synchronization overhead.

Package base64 constants

Package base64 error definitions

Package base64 utilities and encoding instances

Index

• Constants
• Variables
• func DecodeString(str string) ([]byte, error)
• func EncodeToString(data []byte) string
• func EncodeToStringSafe(data []byte) (string, error)

Constants

const I2PEncodeAlphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-~"

I2PEncodeAlphabet defines the I2P-specific base64 character set used throughout the network. This alphabet follows RFC 4648 standard base64 encoding with two critical modifications: - "/" is replaced with "~" to avoid filesystem path conflicts - "+" is replaced with "-" to ensure URL-safe encoding without percent-encoding The alphabet maintains the standard ordering: A-Z (0-25), a-z (26-51), 0-9 (52-61), - (62), ~ (63). This encoding is essential for I2P destination addresses, router identifiers, and network data structures. Example usage: Used in .b64.i2p addresses and binary data serialization across I2P protocols.

const MAX_ENCODE_SIZE = 10 * 1024 * 1024 // 10 MB

MAX_ENCODE_SIZE defines the maximum number of bytes that can be base64 encoded in a single operation. This limit prevents excessive memory allocation and ensures reasonable processing times. The limit of 10MB is sufficient for all I2P protocol needs including router infos, destinations, and lease sets, while preventing potential DoS through memory exhaustion.

Variables

var (
	// ErrEmptyData is returned when attempting to encode empty data.
	// Empty data cannot be meaningfully encoded and likely indicates a programming error.
	ErrEmptyData = errors.New("cannot encode empty data")

	// ErrDataTooLarge is returned when data exceeds MAX_ENCODE_SIZE.
	// This prevents excessive memory allocation and potential DoS attacks.
	ErrDataTooLarge = errors.New("data exceeds maximum encodable size")
)

var I2PEncoding *b64.Encoding = b64.NewEncoding(I2PEncodeAlphabet)

I2PEncoding provides the standard base64 encoder/decoder instance for all I2P components. This encoding instance is pre-configured with the I2P-specific alphabet and optimizes performance by reusing the same encoder across multiple operations. It handles the complex character mapping required for I2P network compatibility while maintaining standard base64 semantics. The instance is thread-safe and can be used concurrently across goroutines. Example: Used internally by EncodeToString and DecodeString for consistent encoding behavior.

Functions

func DecodeString

func DecodeString(str string) ([]byte, error)

DecodeString converts I2P-compatible base64 strings back to their original binary form. This function reverses the encoding process, taking base64 strings that use I2P's alphabet and converting them back to the original byte data. It validates input characters against the I2P alphabet and handles standard base64 padding requirements. Returns an error if the input contains invalid characters or malformed padding. Example: DecodeString("SGVsbG8-") returns []byte{72, 101, 108, 108, 111}, nil (Hello decoded)

func EncodeToString

func EncodeToString(data []byte) string

EncodeToString converts arbitrary binary data to I2P-compatible base64 string representation. This function takes raw byte data and produces a human-readable string using I2P's modified base64 alphabet. The output is compatible with I2P destination addresses, router identifiers, and other network protocol elements that require base64 encoding. The encoding process applies standard base64 padding rules with '=' characters as needed. Example: EncodeToString([]byte{72, 101, 108, 108, 111}) returns "SGVsbG8-" (Hello in I2P base64)

func EncodeToStringSafe

func EncodeToStringSafe(data []byte) (string, error)

EncodeToStringSafe encodes binary data to a base64 string with input validation. Unlike EncodeToString, this function validates the input data size to prevent excessive memory allocation and potential DoS attacks. Use this function when encoding untrusted or user-provided data. Returns an error if data is empty or exceeds MAX_ENCODE_SIZE. Example: EncodeToStringSafe([]byte{72, 101, 108, 108, 111}) returns "SGVsbG8-", nil