PowerShell function to compare a locally generated cryptographic hash for a given file against a remotely provided one. Useful for insuring the integrity/authenticity of downloaded files.
The function makes use of the existing PowerShell cmdlet 'Get-FileHash' to generate the desired hash, I simply extend the functionality to allow for a comparison.
- Algorithm - Accepted values are MD5, SHA1, SHA256, SHA384, SHA512
- Hash - The provided cryptographic hash value to be validated against
- Path - The path to the file which will be hashed
Here we see an example where the provided and generated hash values are a match:
PS C:\> Compare-Hash -Algorithm SHA1 -Hash F9A1856F7AD4733F4BB3D84A45DEA612ADD819D6 -Path C:\temp\ComputerName.exe
MATCH
Now we see an example where the provided and generated hash values do not match:
PS C:\> Compare-Hash -Algorithm SHA1 -Hash DA39A3EE5E6B4B0D3255BFEF95601890AFD80709 -Path C:\temp\ComputerName.exe
NO MATCH
This function depends on the Get-FileHash cmdlet which is native to PowerShell version 4.0; therefore the system must be running at least version 4.0 or above for this function to work correctly.
The function outputs a System.String value, the results of the Get-Member ouput are provided below for reference.
TypeName: System.String
Name MemberType Definition
---- ---------- ----------
Clone Method System.Object Clone(), System.Object ICloneable.Clone()
CompareTo Method int CompareTo(System.Object value), int CompareTo(string strB), int IComparable.CompareTo(System.Object obj...
Contains Method bool Contains(string value)
CopyTo Method void CopyTo(int sourceIndex, char[] destination, int destinationIndex, int count)
EndsWith Method bool EndsWith(string value), bool EndsWith(string value, System.StringComparison comparisonType), bool Ends...
Equals Method bool Equals(System.Object obj), bool Equals(string value), bool Equals(string value, System.StringCompariso...
GetEnumerator Method System.CharEnumerator GetEnumerator(), System.Collections.IEnumerator IEnumerable.GetEnumerator(), System.C...
GetHashCode Method int GetHashCode()
GetType Method type GetType()
GetTypeCode Method System.TypeCode GetTypeCode(), System.TypeCode IConvertible.GetTypeCode()
IndexOf Method int IndexOf(char value), int IndexOf(char value, int startIndex), int IndexOf(char value, int startIndex, i...
IndexOfAny Method int IndexOfAny(char[] anyOf), int IndexOfAny(char[] anyOf, int startIndex), int IndexOfAny(char[] anyOf, in...
Insert Method string Insert(int startIndex, string value)
IsNormalized Method bool IsNormalized(), bool IsNormalized(System.Text.NormalizationForm normalizationForm)
LastIndexOf Method int LastIndexOf(char value), int LastIndexOf(char value, int startIndex), int LastIndexOf(char value, int s...
LastIndexOfAny Method int LastIndexOfAny(char[] anyOf), int LastIndexOfAny(char[] anyOf, int startIndex), int LastIndexOfAny(char...
Normalize Method string Normalize(), string Normalize(System.Text.NormalizationForm normalizationForm)
PadLeft Method string PadLeft(int totalWidth), string PadLeft(int totalWidth, char paddingChar)
PadRight Method string PadRight(int totalWidth), string PadRight(int totalWidth, char paddingChar)
Remove Method string Remove(int startIndex, int count), string Remove(int startIndex)
Replace Method string Replace(char oldChar, char newChar), string Replace(string oldValue, string newValue)
Split Method string[] Split(Params char[] separator), string[] Split(char[] separator, int count), string[] Split(char[]...
StartsWith Method bool StartsWith(string value), bool StartsWith(string value, System.StringComparison comparisonType), bool ...
Substring Method string Substring(int startIndex), string Substring(int startIndex, int length)
ToBoolean Method bool IConvertible.ToBoolean(System.IFormatProvider provider)
ToByte Method byte IConvertible.ToByte(System.IFormatProvider provider)
ToChar Method char IConvertible.ToChar(System.IFormatProvider provider)
ToCharArray Method char[] ToCharArray(), char[] ToCharArray(int startIndex, int length)
ToDateTime Method datetime IConvertible.ToDateTime(System.IFormatProvider provider)
ToDecimal Method decimal IConvertible.ToDecimal(System.IFormatProvider provider)
ToDouble Method double IConvertible.ToDouble(System.IFormatProvider provider)
ToInt16 Method int16 IConvertible.ToInt16(System.IFormatProvider provider)
ToInt32 Method int IConvertible.ToInt32(System.IFormatProvider provider)
ToInt64 Method long IConvertible.ToInt64(System.IFormatProvider provider)
ToLower Method string ToLower(), string ToLower(cultureinfo culture)
ToLowerInvariant Method string ToLowerInvariant()
ToSByte Method sbyte IConvertible.ToSByte(System.IFormatProvider provider)
ToSingle Method float IConvertible.ToSingle(System.IFormatProvider provider)
ToString Method string ToString(), string ToString(System.IFormatProvider provider), string IConvertible.ToString(System.IF...
ToType Method System.Object IConvertible.ToType(type conversionType, System.IFormatProvider provider)
ToUInt16 Method uint16 IConvertible.ToUInt16(System.IFormatProvider provider)
ToUInt32 Method uint32 IConvertible.ToUInt32(System.IFormatProvider provider)
ToUInt64 Method uint64 IConvertible.ToUInt64(System.IFormatProvider provider)
ToUpper Method string ToUpper(), string ToUpper(cultureinfo culture)
ToUpperInvariant Method string ToUpperInvariant()
Trim Method string Trim(Params char[] trimChars), string Trim()
TrimEnd Method string TrimEnd(Params char[] trimChars)
TrimStart Method string TrimStart(Params char[] trimChars)
Chars ParameterizedProperty char Chars(int index) {get;}
Length Property int Length {get;}