Powershell extract multiple occurrences in multi-lines - regex

Question

I have a text file that has thousands of binary certificates, this is a sample of it.
Row 1:
Binary Certificate:
-----BEGIN CERTIFICATE-----
MIIFtzCCBJ+gAwIBAgIKGUNYAwAAAAAAODANBgkqhkiG9w0BAQsFADBxMQswCQYD
VQQGEwJERTEcMBoGA1UECBMTTm9yZHJoZWluLVdlc3RmYWxlbjENMAsGA1UEBxME
Qm9ubjEWMBQGA1UEChMNRGV1dHNjaGUgUG9zdDEdMBsGA1UEAxMURFBESEwgVExT
-----END CERTIFICATE-----
Row 2:
Binary Certificate:
-----BEGIN CERTIFICATE-----
MIIGEzCCBPugAwIBAgIKGVe6uwAAAAAAOTANBgkqhkiG9w0BAQsFADBxMQswCQYD
VQQGEwJERTEcMBoGA1UECBMTTm9yZHJoZWluLVdlc3RmYWxlbjENMAsGA1UEBxME
Qm9ubjEWMBQGA1UEChMNRGV1dHNjaGUgUG9zdDEdMBsGA1UEAxMURFBESEwgVExT
-----END CERTIFICATE-----
Row 3:
Binary Certificate:
-----BEGIN CERTIFICATE-----
MIIGMzCCBRugAwIBAgIKGYrkyAAAAAAAOjANBgkqhkiG9w0BAQsFADBxMQswCQYD
VQQGEwJERTEcMBoGA1UECBMTTm9yZHJoZWluLVdlc3RmYWxlbjENMAsGA1UEBxME
Qm9ubjEWMBQGA1UEChMNRGV1dHNjaGUgUG9zdDEdMBsGA1UEAxMURFBESEwgVExT
-----END CERTIFICATE
I need to output each certificate to a separate file. What I'm struggling with is how to extract from "-----BEGIN CERTIFICATE-----" all the way to the first "-----END CERTIFICATE-----" to save it to a variable/file, then go and find the next match and so on.
The output of each match should look like this:
-----BEGIN CERTIFICATE-----
MIIFtzCCBJ+gAwIBAgIKGUNYAwAAAAAAODANBgkqhkiG9w0BAQsFADBxMQswCQYD
VQQGEwJERTEcMBoGA1UECBMTTm9yZHJoZWluLVdlc3RmYWxlbjENMAsGA1UEBxME
Qm9ubjEWMBQGA1UEChMNRGV1dHNjaGUgUG9zdDEdMBsGA1UEAxMURFBESEwgVExT
-----END CERTIFICATE-----
I have tried multiple Regex's with no luck :[
Is there a way, whether Regex or String.Split that can do this match/split?

Answer 1

If the contents are exactly like you stated above then this should work on extracting the Key.
$File = "C:\Test.txt"
$content = Get-Content $file
$contents = $content
$Complete = [regex]::split($contents, "BEGIN CERTIFICATE-----(.*?)-----END CERTIFICATE")
for($i = 1; $i -lt $Complete.Length; $i =$i+2){
$Complete[$i] -replace " ","`r`n"
}

Answer 2

This script will read file sample.pem and save each found certificate incrementing the number to cert#.pem
## Q:\Test\2017\08\25\SO_45884754.ps1
$Pattern = '(?smi)^-{2,}BEGIN CERTIFICATE-{2,}.*?-{2,}END CERTIFICATE-{2,}'
Get-Content .\sample.PEM -raw |
Select-String -Pattern $Pattern -Allmatches|
ForEach-Object {$Cnt=0;$_.Matches}| ForEach-Object {
$Cnt++
Set-Content -Value $_.Value -Path ("Cert{0}.pem" -f $Cnt)
}

Answer 3

There may be several ways to this. PowerShell 5 has a new feature that can be used to detect patterns, for example. Anything is possible with regex, though it is always a bit cryptic. If you wanted to do good ol' easy to read/understand script, you could do something like this:
$begin_certificate='-----BEGIN CERTIFICATE'
$end_certificate ='-----END CERTIFICATE'
[System.Collections.ArrayList]$certs=#()
$add_next = $false
$all_certs = get-content C:\Temp\a.txt
Foreach ($line in $all_certs) {
if ( $line.StartsWith($begin_certificate)) {
$add_next = $true
$cert_content = $begin_certificate
continue
}
if ($add_next) {
$cert_content += "`n$line"
if ($line.StartsWith($end_certificate)) {
$add_next = $false
[void]$certs.add($cert_content) # don't print the result of operation
}
}
}
# This array list has all the certs now
$certs
With the file sample you have given above, you would get 3 items in certs and following as output:
-----BEGIN CERTIFICATE
MIIFtzCCBJ+gAwIBAgIKGUNYAwAAAAAAODANBgkqhkiG9w0BAQsFADBxMQswCQYD
VQQGEwJERTEcMBoGA1UECBMTTm9yZHJoZWluLVdlc3RmYWxlbjENMAsGA1UEBxME
Qm9ubjEWMBQGA1UEChMNRGV1dHNjaGUgUG9zdDEdMBsGA1UEAxMURFBESEwgVExT
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE
MIIGEzCCBPugAwIBAgIKGVe6uwAAAAAAOTANBgkqhkiG9w0BAQsFADBxMQswCQYD
VQQGEwJERTEcMBoGA1UECBMTTm9yZHJoZWluLVdlc3RmYWxlbjENMAsGA1UEBxME
Qm9ubjEWMBQGA1UEChMNRGV1dHNjaGUgUG9zdDEdMBsGA1UEAxMURFBESEwgVExT
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE
MIIGMzCCBRugAwIBAgIKGYrkyAAAAAAAOjANBgkqhkiG9w0BAQsFADBxMQswCQYD
VQQGEwJERTEcMBoGA1UECBMTTm9yZHJoZWluLVdlc3RmYWxlbjENMAsGA1UEBxME
Qm9ubjEWMBQGA1UEChMNRGV1dHNjaGUgUG9zdDEdMBsGA1UEAxMURFBESEwgVExT
-----END CERTIFICATE