ハッシュ生成

This hash generator turns exact text input into a fixed-length hexadecimal digest in the browser. It is useful when you need a stable value for comparison, integrity checking, API signing preparation, or compatibility with a system that asks for a specific SHA result. The output is not encrypted text and cannot be decrypted back into the original input.

How SHA digests are produced

SHA algorithms first encode the message as bytes, pad it into fixed-size blocks, and repeatedly mix each block into an internal state with bitwise operations. A small input change should produce a very different digest, which is why the value is good for comparison but not useful as recoverable storage. SHA-224 belongs to SHA-2: it uses the SHA-256 compression structure with different initial values and emits the first 224 bits of the final state.

• SHA-1 emits 160 bits and is kept mainly for legacy compatibility because practical collision attacks exist.
• SHA-224 and SHA-256 both use 512-bit message blocks and 32-bit operations, but their output lengths and initial values differ.
• SHA-384 and SHA-512 use 1024-bit blocks with 64-bit operations, so their digests are longer and often appear in stricter compatibility policies.

このツールの使い方

1. Choose the SHA algorithm that matches your compatibility or integrity-check requirement before hashing the input.
2. Paste the exact text you want to hash, then compare whitespace and line endings carefully.
3. Copy the digest only after it matches the expected algorithm, casing, and byte-for-byte source content.

A reliable text hashing workflow

Hashing looks like a one-click operation, but most wrong results come from choosing the wrong algorithm or hashing a slightly different string. Treat the algorithm name, input bytes, and output format as one set of evidence.

1. Choose the algorithm required by the downstream system before pasting the text.
2. Keep the text exactly as it should be hashed, including spaces, tabs, punctuation, and trailing newlines.
3. After generating the digest, compare both the length and the hexadecimal characters, not only the beginning of the string.

Classic sample: the text `abc`

The short string `abc` is a useful test case because many SHA implementations publish the same known digests. It also shows why algorithm names cannot be mixed: the same input produces different output lengths and values under SHA-224 and SHA-256.

Known digests for `abc`

Input:
abc

SHA-224:
23097d223405d8228642a477bda255b32aadbce4bda0b3f7e36c9da7

SHA-256:
ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad

Minimal Web Crypto digest example

const bytes = new TextEncoder().encode("abc");
const digest = await crypto.subtle.digest("SHA-256", bytes);

Implementation note

Browser Web Crypto exposes SHA-1, SHA-256, SHA-384, and SHA-512 through `crypto.subtle.digest()`. This tool computes SHA-224 locally with a SHA-256-family implementation because SHA-224 is not exposed by that browser API.

Where this tool is useful

Use this tool when the source content is text and the next step expects a SHA digest. Typical examples include comparing copied payloads, checking whether a configuration value changed, preparing the digest portion of an API signing process, and reproducing a checksum-like value used by another system.

よくある使い方

ハッシュ生成 は、ブラウザを離れずに短く反復的な作業をすばやく片づけたい場面向けに設計されています。

• ドキュメント、チケット、リリースノートを書きながら小さな値を素早く確認する。
• チームメンバーや顧客へ共有する前に、コピーした内容を整える。
• 表計算、IDE、デスクトップアプリを開かず、同じ変換を繰り返す。

How Hash Checks Fail in Practice

Hash comparisons fail most often because teams compare the wrong bytes, the wrong algorithm, or the wrong normalization assumptions. The browser result is useful only when those three inputs are aligned.

• Confirm the destination expects the same algorithm before comparing any digest values.
• Keep the raw source nearby when copied text may have lost invisible byte details.
• Use stronger SHA variants for new trust-sensitive workflows and keep weaker ones only for compatibility.

Mistakes that make SHA results look wrong

When a digest does not match, the algorithm implementation is rarely the first suspect. In everyday work, the mismatch is more often caused by invisible input differences, a different character encoding, pasted wrapper text, or a downstream system using another SHA variant.

• A trailing newline or an extra space is part of the input and will change the digest.
• Do not use SHA-1 for new security-sensitive designs; keep it only when a legacy protocol requires that exact value.
• Do not treat a fast SHA digest as password storage; password storage needs a slow password-hashing scheme with salt and cost settings.

What a hash can and cannot prove

A matching hash strongly suggests the same content under the same algorithm, but a hash alone does not prove authorship, secrecy, or trust. Those properties require signatures, authentication, or transport controls around the digest.

SHA algorithms available in this tool

実用上の注意

• ハッシュ生成 は既定でブラウザ内で動作するため、別のツールチェーンを用意せずにすばやくローカル確認を行えます。
• 実際の入力が大きい、機密性が高い、または業務上重要な場合は、まず代表的なサンプルから始めてください。
• 本番環境、顧客向け、法務、財務、安全性が重要な作業に使う前に、最終結果を必ず確認してください。

ハッシュ生成 の参考情報

ハッシュ生成 は、ダイジェストアルゴリズム、完全性チェック、ハッシュが暗号化ではない理由を説明します。

• SHA 系のハッシュはメッセージを固定サイズのブロックで処理し、各ブロックを内部状態へ繰り返し混ぜ込み、最後に固定長のダイジェストを出力します。
• SHA-1 は 512 ビットブロックと 160 ビット出力を使いますが、実用的な衝突攻撃があるため互換性目的に限るべきです。
• SHA-256 は 512 ビットブロックと 32 ビット演算を使い、SHA-384 と SHA-512 は 1024 ビットブロックと 64 ビット演算を使います。SHA-384 は異なる初期値を持つ切り詰め版 SHA-512 と考えられます。
• ハッシュは復号できません。既知のダイジェストと比較して確認します。

参考資料

• FIPS 180-4: Secure Hash Standard (SHS)
• MDN: SubtleCrypto.digest()
• NIST Policy on Hash Functions